My model is as below

 public class FItem

        {

            public FItem()

            {

                FSubsystems = new List<FSubsystem>();

                FReferences = new List<FReference>();

                FWildcards = new List<FWildcard>();

            }

            public int RecordId { get; set; }

            public int MarketId { get; set; }

            public string ItemName { get; set; }

            public string ItemFamily { get; set; }

            public string HoverFamily { get; set; }

            public string ItemDesc { get; set; }

            public int? FixedSiteDetail { get; set; }

            public int? ItemPathID { get; set; }

            |
            | remainig properties here .....

            public List<FSubsystem> FSubsystems { get; set; }

            public List<FReference> FReferences { get; set; }

            public List<FWildcard> FWildcards { get; set; }

        }

I bind this model to a xamdatagrid via viewmodel . My xamCode is as below

 <igDP:XamDataGrid  Name="dgRecords" DataSource="{Binding FItems, Mode=TwoWay}" ScrollingMode="DeferredWithScrollTips" MaxHeight="500" MinHeight="300"  Theme="IGTheme"

                           RecordContainerGenerationMode="Virtualize"  ScrollBehaviorOnListChange="PreserveRecordsInView" FieldLayoutInitialized="dgRecords_FieldLayoutInitialized">

                    <igDP:XamDataGrid.ViewSettings>

                        <igDP:GridViewSettings />

                    </igDP:XamDataGrid.ViewSettings>

                    <igDP:XamDataGrid.FieldLayoutSettings >

                        <igDP:FieldLayoutSettings AutoGenerateFields="True"  AllowAddNew="True"

AddNewRecordLocation="OnTopFixed"/>

                    </igDP:XamDataGrid.FieldLayoutSettings>

                    <igDP:XamDataGrid.FieldLayouts>

                        <igDP:FieldLayout/>

                    </igDP:XamDataGrid.FieldLayouts>

                    <igDP:XamDataGrid.FieldSettings>

                        <igDP:FieldSettings AllowRecordFiltering="True" AllowSummaries="True" AllowEdit="True" AutoSizeScope="ViewableRecords" />

                    </igDP:XamDataGrid.FieldSettings>

                </igDP:XamDataGrid>

I auto generate columns .

I am getting button to add new rows to Fitem grid . But I am not  able to add new rows to inner grids (FSubsystems ,FReferences,FWildcards). 

How can I add rows to inner grids ?