Thank you for your feedback Kris. That could be helpful for other users as well.

The approach I took was to have one content pane within a split pane and then use a GridSplitter control. So like your first suggestion. Your second suggestion is what I was trying to do initially but could not figure out the combinations. If the user does not like the first approach I'll have to go with the second. 

Thanks for the suggestions. 

Hello Kris,

There are two more approaches that I would like to provide to you and that could be helpful in your scenario.
If you would like to display two controls and move them together, you can try using one ContentPane that has a Grid with two columns and a GridSplitter between them.
Another approach would be to create a single content pane for each grouping of the two controls and put a XamDockManager within the ContentPane. In that case the LayoutMode property of the “inner” XamDockManager should be set to FillContainer. That manager can have a SplitPane with two panes which have the dragging functionality disabled. One thing to mention here is that the XamDockManager would be a header for the “outer” content pane that can be dragged and for the “inner” content panes that could not be dragged. Of course, the dragging in the “inner” dockmanager could be allowed, although this could be a little confusing for the end user as the dragging between different dockmanager is not allowed so the panes in the “inner” dockmanager would be dragged only within it.