I've been trying unsuccessfully to add a custom action to the ribbon on new form for a document set (NewDocSet.aspx). There seems to be no reference to this location in the standard locations listed on MSDN, but appears to include the Ribbon.DocLibList.Edit tab. I'm able to add a custom action to the edit form of the document set successfully, and have found plenty of references on how to add custom actions to the Manage Document Set group, but have not found a way to add it to the new form.
I'm trying to create the custom action in order to pre-fill some data that the user will search for using a custom form. I'd like to make this metadata required and so I'd like to have the custom action in the new form as well as the edit form (it works perfectly in the edit form).
Any help would be greatly appreciated.