Bridging member db across 4 forums

[soundbarrierpro]

Hi,

I've recently come together on collaboration to create an umbrella site for all sports franchises in our city.

The owner of the domains has all of the domains hosted on one plan. There is the main domain, then 4 sub domains. Each domain will have it's own forum.

Is there a mod to share the member db table across all four forums hosted? We'd like the forums to have seem less integration so that members don't have to log into each one separately.

Thank you for any help!