Sharing a common user base with a collaborating forum

[mepusica]

Hi

I'm not sure if this is the right place to ask this question, but here goes nothing.

I want to collaborate with another Vbulletin forum without actually merging our two individual forums.

We want to be able to share a common userbase so that people who sign up to one forum are automatically signed up to the other.

In addition I want to mirror some of my subforums on my collaborator's forum in such a way so that posts written on these mirrored subforums on my collaborator's forum are automatically displayed on my forum and vice versa.

I am seeking this solution so my collaborator and I can maintain full ownership and freedom to operate in our respective forums, but at the same time share a common community.

Is this possible?