Bridging communities

Has anyone bridged two Verint communities? I am building a second Verint community and am interested in knowing other's experiences. I have done this in the past with another vendor but am not familiar with the options in Verint.

Can we create a unified search across both communities?

Can we synch profiles between two communities? Editing of profiles only having to be done in one place.

What about one username across two communities?

The flow would be similar to below:

user registers > creates community username > API call is made to community A & B to create the profile > update to profile in community A reflects change in community B

My concern is legacy users. Is that a migration of profiles? I feel that will muddy the waters as we want to know exactly how many new users each community has attracted.

I know lots of questions. I appreciate anyone's input.