A scrollbar is used to expose the scroll range - not define it - if that is what you mean. This is the same in any scrollable control. In the case of the xamSchedule the timeslots are a minimum width based on the preferrred width of a ScheduleViewTimeslotHeader. If there is less room than required to show all the timeslots horizontally using that value then scrolling is enabled whether a scrollbar is present or not. I thought you wanted to have the scrolling of all synchronized but only shown in 1 control. If you want that you should just create some attached properties to help with that. For example, you might create one for the scrollbar offset. You can use a two-way binding between the offset of the scrollbar to the control and then two way bind between that property on the control and another xamschedule. e.g.

    <Grid xmlns:tshelper="clr-namespace:ScheduleHelper">
        <Grid.Resources>
            <igPrim:ScheduleResourceString x:Key="BlockingErrorLiteral" ResourceName="BlockingErrorLiteral"/>

            <igPrim:ValueConverterGroup x:Key="nullToVisibility">
                <!-- if null sets visibility to Collapsed -->
                <igPrim:FixedValueConverter SourceValue="{x:Null}">
                    <igPrim:FixedValueConverter.DestinationValue>
                        <Visibility>Collapsed</Visibility>
                    </igPrim:FixedValueConverter.DestinationValue>
                </igPrim:FixedValueConverter>
                <!-- if not null sets visibility to Visible -->
                <igPrim:FixedValueConverter>
                    <igPrim:FixedValueConverter.DestinationValue>
                        <Visibility>Visible</Visibility>
                    </igPrim:FixedValueConverter.DestinationValue>
                </igPrim:FixedValueConverter>
            </igPrim:ValueConverterGroup>
            <Style x:Key="BlockingErrorStyle" TargetType="ContentControl">
                <!-- AS 12/16/10 TFS61923 -->
                <Setter Property="igPrim:XamlHelper.Focusable" Value="False"/>
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="ContentControl">
                            <Grid >
                                <Grid.RowDefinitions>
                                    <RowDefinition Height ="Auto"/>
                                    <RowDefinition Height ="Auto"/>
                                    <RowDefinition Height ="*"/>
                                </Grid.RowDefinitions>
                                <Rectangle Grid.RowSpan="3"
            Opacity=".9"
            Fill="{Binding Path=(igPrim:CalendarBrushProvider.BrushProvider)[BlockingErrorBackground], RelativeSource={RelativeSource TemplatedParent}}"/>
                                <!--Header-->
                                <ContentControl
       Grid.Row="0"
       FontWeight="Bold"
       Foreground="{Binding Path=(igPrim:CalendarBrushProvider.BrushProvider)[BlockingErrorHeaderForeground], RelativeSource={RelativeSource TemplatedParent}}"
       Content="{Binding Source={StaticResource BlockingErrorLiteral}, Path=Value}"
       Margin="5">
                                    <ContentControl.FontSize>
                                        <Binding Path="FontSize" RelativeSource="{RelativeSource TemplatedParent}">
                                            <Binding.Converter>
                                                <igPrim:MinMaxConverter MinValue="14"/>
                                            </Binding.Converter>
                                        </Binding>
                                    </ContentControl.FontSize>
                                    <!-- JJD 9/19/11 - TFS87912
        Use binding instead to the Value property of the ScheduleResourceString
        so we can get notified when the resources are changed.
       <igPrim:ScheduleResourceString ResourceName="BlockingErrorLiteral"/>-->
                                </ContentControl>
                                <!--Description-->
                                <TextBlock
       Grid.Row="1"
       Margin="5,0,5,0"
       FontWeight="Bold"
       TextWrapping="Wrap"
       Foreground="{Binding Path=(igPrim:CalendarBrushProvider.BrushProvider)[BlockingErrorForeground], RelativeSource={RelativeSource TemplatedParent}}"
       Text="{Binding Path=Content.UserErrorText, RelativeSource={RelativeSource TemplatedParent}}"
       Visibility="{Binding Path=Content.UserErrorText, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource nullToVisibility}}"
       >
       <TextBlock.FontSize>
        <Binding Path="FontSize" RelativeSource="{RelativeSource TemplatedParent}">
         <Binding.Converter>
          <igPrim:MinMaxConverter MinValue="12.5"/>
         </Binding.Converter>
        </Binding>
       </TextBlock.FontSize>
                                </TextBlock>
                                <!--Details-->
                                <ScrollViewer Grid.Row="2"
             Margin="5"
             HorizontalScrollBarVisibility="Auto"
             VerticalScrollBarVisibility="Auto">
                                    <TextBox 
        Text="{Binding Path=Content, Mode=OneWay, RelativeSource={RelativeSource TemplatedParent}}"
        Foreground="{Binding Path=(igPrim:CalendarBrushProvider.BrushProvider)[BlockingErrorForeground], RelativeSource={RelativeSource TemplatedParent}}"
        IsReadOnly="True"
        TextWrapping="Wrap"
        Background="{x:Null}"/>
                                </ScrollViewer>
                            </Grid>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
            <Style TargetType="ig:XamScheduleView">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="ig:XamScheduleView">
                            <Border BorderBrush="{TemplateBinding BorderBrush}"
       BorderThickness="{TemplateBinding BorderThickness}"
       Background="{TemplateBinding Background}"
       Padding="{TemplateBinding Padding}"
       igPrim:XamlHelper.SnapsToDevicePixels="True">
                                <VisualStateManager.VisualStateGroups>
                                    <VisualStateGroup Name="ErrorStates">
                                        <VisualState Name="NoError"/>
                                        <VisualState Name="Error">
                                            <Storyboard Storyboard.TargetName="ErrorDisplay" Storyboard.TargetProperty="Visibility">
                                                <ObjectAnimationUsingKeyFrames>
                                                    <DiscreteObjectKeyFrame KeyTime="0">
                                                        <DiscreteObjectKeyFrame.Value>
                                                            <Visibility>Visible</Visibility>
                                                        </DiscreteObjectKeyFrame.Value>
                                                    </DiscreteObjectKeyFrame>
                                                </ObjectAnimationUsingKeyFrames>
                                            </Storyboard>
                                        </VisualState>
                                    </VisualStateGroup>
                                </VisualStateManager.VisualStateGroups>
                                <Grid x:Name="RootPanel" >
                                    <ig:GridBagPanel igPrim:XamlHelper.SnapsToDevicePixels="{TemplateBinding igPrim:XamlHelper.SnapsToDevicePixels}">
                                        <TextBlock Text="{TemplateBinding SecondaryTimeZoneLabel}" 
          VerticalAlignment="Top"
          HorizontalAlignment="Right"
          Margin="0,6,8,0"
          ig:GridBagPanel.Row="0" 
          ig:GridBagPanel.Column="0" 
          Visibility="{TemplateBinding SecondaryTimeZoneVisibility}" />
                                        <TextBlock Text="{TemplateBinding PrimaryTimeZoneLabel}" 
          VerticalAlignment="Top"
          HorizontalAlignment="Right"
          Margin="0,6,8,0"
          ig:GridBagPanel.Row="1" 
          ig:GridBagPanel.Column="0" />
                                        <igPrim:ScheduleViewTimeslotHeaderArea 
          x:Name="SecondaryTimeZone" 
          Background="{Binding Path=DefaultBrushProvider[TimeslotHeaderAreaBackgroundScheduleView], RelativeSource={RelativeSource TemplatedParent}}"
          BorderBrush="{Binding Path=DefaultBrushProvider[TimeslotHeaderAreaSeparator], RelativeSource={RelativeSource TemplatedParent}}"
          BorderThickness="0,0,0,1"
          ig:GridBagPanel.Row="0" 
          ig:GridBagPanel.Column="2" 
          Visibility="{TemplateBinding SecondaryTimeZoneVisibility}" 
          ig:GridBagPanel.ColumnWeight="1" />
                                        <igPrim:ScheduleViewTimeslotHeaderArea 
          x:Name="PrimaryTimeZone" 
          Background="{Binding Path=DefaultBrushProvider[TimeslotHeaderAreaBackgroundScheduleView], RelativeSource={RelativeSource TemplatedParent}}"
          ig:GridBagPanel.Row="1" 
          ig:GridBagPanel.Column="2" 
          ig:GridBagPanel.ColumnWeight="1" />
                                        <igPrim:ScheduleStackPanel 
          x:Name="GroupHeadersPanel" 
          ig:GridBagPanel.Row="2" 
          ig:GridBagPanel.Column="0" 
          ig:GridBagPanel.RowWeight="1" 
          Visibility="{TemplateBinding CalendarHeaderAreaVisibilityResolved}"
         />
                                        <igPrim:ScheduleStackPanel 
          x:Name="GroupsPanel" 
          ig:GridBagPanel.Row="2" 
          ig:GridBagPanel.Column="2" 
          ig:GridBagPanel.ColumnWeight="1"
          ig:GridBagPanel.RowWeight="1" />
                                        <ScrollBar 
          ig:GridBagPanel.Column="3" 
          ig:GridBagPanel.Row="2" 
          Orientation="Vertical" 
           Style="{TemplateBinding ScrollBarStyle}"
          x:Name="TimeslotGroupScrollBar" 
          ig:GridBagPanel.RowWeight="1" />
                                        <ScrollBar 
          ig:GridBagPanel.Column="2" 
          ig:GridBagPanel.Row="3" 
          ig:GridBagPanel.ColumnWeight="1"
          Orientation="Horizontal"
             Style="{TemplateBinding ScrollBarStyle}"
                                        MinHeight="0"
                                        ig:GridBagPanel.PreferredHeight="{TemplateBinding tshelper:TimeslotHelper.ScrollBarHeight}"
                                        Value="{Binding Path=(tshelper:TimeslotHelper.ScrollBarOffset), RelativeSource={RelativeSource TemplatedParent}, Mode=TwoWay}"
          x:Name="TimeslotScrollBar" />
                                        <Rectangle
          igPrim:XamlHelper.SnapsToDevicePixels="True"
          Fill="{Binding Path=DefaultBrushProvider[TimeslotHeaderTickmarkScheduleView], RelativeSource={RelativeSource TemplatedParent}}"
          ig:GridBagPanel.Row="0"
          ig:GridBagPanel.Column="1"
          ig:GridBagPanel.RowSpan="4"
          ig:GridBagPanel.ColumnWeight="0"
          ig:GridBagPanel.PreferredWidth="1"
                                                  Width="2"/>
                                        <!-- AS 11/11/10 NA 11.1 - CalendarHeaderAreaWidth -->
                                        <!-- Overlap the rectangle above. -->
                                        <igPrim:ScheduleResizerBar 
         x:Name="GroupHeadersResizer"
         IsEnabled="{TemplateBinding AllowCalendarHeaderAreaResizing}"
         Canvas.ZIndex="2"
         Width="4"
         ig:GridBagPanel.Column="0" 
         ig:GridBagPanel.ColumnSpan="2" 
         ig:GridBagPanel.Row="0"
         ig:GridBagPanel.RowSpan="4" 
         HorizontalAlignment="Right"
         />
                                    </ig:GridBagPanel>
                                    <ContentControl x:Name="ErrorDisplay" 
               Visibility="Collapsed" 
               Content="{Binding Path=BlockingError, RelativeSource={RelativeSource TemplatedParent}}"
               Style="{StaticResource BlockingErrorStyle}"
               igPrim:CalendarBrushProvider.BrushProvider="{Binding Path=DefaultBrushProvider, RelativeSource={RelativeSource TemplatedParent}}"
               />
                                </Grid>
                            </Border>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </Grid.Resources>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <ig:XamScheduleView DataManager="{Binding ElementName=dm}" x:Name="sv1" Grid.Row="0" tshelper:TimeslotHelper.ScrollBarHeight="0" tshelper:TimeslotHelper.ScrollBarOffset="{Binding ElementName=sv4, Mode=TwoWay, Path=(tshelper:TimeslotHelper.ScrollBarOffset)}" />
        <ig:XamScheduleView DataManager="{Binding ElementName=dm}" x:Name="sv2" Grid.Row="1" tshelper:TimeslotHelper.ScrollBarHeight="0" tshelper:TimeslotHelper.ScrollBarOffset="{Binding ElementName=sv4, Mode=TwoWay, Path=(tshelper:TimeslotHelper.ScrollBarOffset)}" />
        <ig:XamScheduleView DataManager="{Binding ElementName=dm}" x:Name="sv3" Grid.Row="2" tshelper:TimeslotHelper.ScrollBarHeight="0" tshelper:TimeslotHelper.ScrollBarOffset="{Binding ElementName=sv4, Mode=TwoWay, Path=(tshelper:TimeslotHelper.ScrollBarOffset)}" />
        <ig:XamScheduleView DataManager="{Binding ElementName=dm}" x:Name="sv4" Grid.Row="3" />
    </Grid>

The TimeslotHelper referenced here is just a simple class with some attached properties. e.g.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;

namespace ScheduleHelper
{
 public static class TimeslotHelper
 {
  #region ScrollBarHeight
  public static readonly DependencyProperty ScrollBarHeightProperty = DependencyProperty.RegisterAttached("ScrollBarHeight",
   typeof(double), typeof(TimeslotHelper),
   new PropertyMetadata(double.NaN)
   );
  public static double GetScrollBarHeight(DependencyObject d)
  {
   return (double)d.GetValue(TimeslotHelper.ScrollBarHeightProperty);
  }
  public static void SetScrollBarHeight(DependencyObject d, double value)
  {
   d.SetValue(TimeslotHelper.ScrollBarHeightProperty, value);
  }
  #endregion //ScrollBarHeight
  #region ScrollBarOffset
  public static readonly DependencyProperty ScrollBarOffsetProperty = DependencyProperty.RegisterAttached("ScrollBarOffset",
   typeof(double), typeof(TimeslotHelper),
   new PropertyMetadata(0d)
   );
  public static double GetScrollBarOffset(DependencyObject d)
  {
   return (double)d.GetValue(TimeslotHelper.ScrollBarOffsetProperty);
  }
  public static void SetScrollBarOffset(DependencyObject d, double value)
  {
   d.SetValue(TimeslotHelper.ScrollBarOffsetProperty, value);
  }
  #endregion //ScrollBarOffset
 }
}

What is happening is that you set the attached ScrollBarHeight on each xamSchedule (except the last) to 0. The template has the preferredheight of the scrollbar bound to that property (and the Minimum of the scrollbar set to 0 since the default style has it set to 17 or maybe its a system value). That allows you to hide the scrollbar from each but the last control. Then the Value property of the ScrollBar is two way bound to the control using the other attached property - ScrollBarOffset. Then each instance of the xamScheduleView has that property two way bound to the last xamSchedule so the scrolling is synchronized.