Thank you for your interest in RadScheduler.
In regards to your questions, RadScheduler does provide an ability for customization of its advanced insert/edit form as well of its inline form. The following online demo shows an example of this case scenario:
As for dragging and dropping appointments from an external control into the RadScheduler itselft -- it is completelly supported by RadScheduler. The following online demos show an example of dragging appointments from a RadGrid and a RadTreeView respectively:
I hope this will help!
the Telerik team
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