The RadTreeListView is best used with hierarchical collections which are of the same data type. With this said, using a hierarchical structure is the advised approach.
As for the Drag and Drop
functionality, please have a look at the respective demo in the WPF Controls Samples
if you have not done so already. I believe it demonstrates just the setup you're looking for.
Please let me know whether I managed to answer your questions. If that is not the case, please elaborate so that I can better assist you. I look forward to your reply.
Want to extend the target reach of your WPF applications, leveraging iOS, Android, and UWP? Try UI for Xamarin
, a suite of polished and feature-rich components for the Xamarin framework, which allow you to write beautiful native mobile apps using a single shared C# codebase.