Ribbon merging should be a general feature, and not tied to MDI appliactions only. For example I am using the Docking LIbrary to implement a "tabbed" interface - each tab can contain a different context that needs to merge its "ribbon" to the main one. 

 Do you have any image that can draw your idea?

I also mean that devexpress Bars should handle the merging of client / mdi bars automatically to the ribbon on mdi-form!

DevExpress should implement this as optional feature to enable in ribbon settings ....