hum.. now your request become far more complicated to execute... different server/system, different security... i don't think this can be done for free... i would not do it myself for free, as it would take some days or even weeks to make the system to be complete.

sharing users table is one thing, sharing a complete independant database is something else. this mean a "Active Sharing" protocol that would update on both sides at the same time, giving vB the same permissions and access to the members even if nobody is involved in the actions.

this is a dream system you wish then... may be possible... at high price!