How to avoid wm::is client group for IS Broker doc types ?


I have a requirement to have Broker document types without starting with general starting client group "wm::is::. For eg. I want to have a Broker document type as x::y::doc. I created IS document type ‘doc’ under folder structure x->y. So the IS document signature is x.y:doc and when I made it publishable, the Broker document type was created as - wm:is::x:y::doc

I can create a new client group with x, but I cannot edit the Broker document type while creating or after it got created. How can I avoid starting client group wm::is::. Can anybody please help ?