Re: Subforms master/Child link
Like most things, there's a (hack) way to do it, however I really question your table set up. Your issue really sounds like a table issue, not a form issue. If the data in subform2 is related to subform1, then it should either be in the same table or subform2 should be a subform of subform1.
I think you should put forms aside for a moment and describe your data better. What table feeds each subform and how are those tables related?