Two Graphs on the same Canvas, interrelated?

[igiovani]

Did anyone cope with anything similar?
Two sets of hierarhical data having some kind of relation between them
but must have each one its own space on the Canvas, its own root node,
its own expansion and could reveal the underlying relations on demand
of the user (of specific node/s each time user selects them)
It looks like the behaviour of roamer of Mark Shepherd's springgraph
(another example is at: www.musicroamer.com) but the multiple subsets
must have some kind of autonomy.

I don't know if it sounds too complicated, most likely it is, but if
anyone has any thought or project relative to it, I' d appreciat it
if anyone responds.

Yiannis