I am afraid that this would not be possible. RadDataFilter is tightly coupled with its underlying view models that are bound to and rely on the UI to create FilterDescriptors. If you dump all of the filtering logic that RadDataFilter performs, you would be left with a empty "dumb" tree-like control. So it will not be RadDataFilter anymore and there will be no one to create the FilterDescriptors.
In your case you would be better off if using some kind of generic "home-made" HeaderedItemsControl such as a a TreeView. You can of course "borrow" UI parts from RadDataFilter, i.e. the plus minus buttons and so forth.
However, if you still decide to replace the Member drop down with something else, you will have to make sure that the underlying view model receives a string with the member name. RadDataFilter can produce filters of the form Member-Operator-Value so you would have to supply a Member anyway. Take a look at the XAML and see how the Member combo-box is bound to the underlying view model.
I don't think that this task would be trivial though. My suggestion would be to use a generic TreeView for your custom purposes.
I hope this helps.
All the best,
the Telerik team
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