WebForm one form-meny sites

Is there any idea to do WebForm for MultiSite? I have such problem: I have meny sites and these sites needs mail form but sometimes I want to change fields in form. The webForm is ideal for this but I have problem with nodes. Becouse the webform needs to add itself to some node and then i may edit it. But other sites have its own {node}'s and don't "see" where is "main form".

Any idea?
Mayby is some solution to share only some node_types....but i think i is not possible (becouse of "nid")