Version merging questions

Hello everybody,

Excuse me if I'm missing something obvious.

Suppose I have two unrelated resources A and B, version graphs VA and
VB, where A belongs to VA and B belongs to VB. Now, if I derive a
version C from A and B, what happens ? C is inserted in both VA and VB
and a new version graph VC containing C is created ? Since a resource
can be in multiple version graphs, does exist a kind of a default
version graph for a given resource ?

Thanks in advance,

Bruno