Since RadDataForm does not know what kind of editor to create for a complex type, you will need to use some custom code to prepare the editor inside the AutoGeneratingField event handler.
The field is ContentControl and inside the handler you may replace the default textbox content , with UI element by your choice.
In case you have troubles implementing this , just send me a small project with your entities and I will implement the missing part regarding the DataForm field generation for the complex type for you .
the Telerik team
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