UltraGridColumn exposes a GroupByEvaluator property, which is of type IGroupByEvaluator. This interface gives you the ability to control which group a row ends up in; it is possible that the DoesGroupContainRow method of the interface is called on each row for each group and there fore might be possible to return true for the same row for more than one group. However, I have to recommend not doing that as I would be very surprised if the grid handled this because you would then have the same instance of an UltraGridRow manifesting itself as two different RowUIElements, which is bound to cause confusion somewhere along the line.

In short, I think the answer is, maybe you can get away with this but probably not and it might be very difficult to know whether it worked properly.