Table reference not maintaining integrity updating record

I tried to search for this and didn't find anything... When I update a record that has a reference to a different table, how is that reference created or maintained?

I have a user, that say, changes their membership. So now that member is ALSO a member of two groups, the original 'membership' and now they are also a 'contributor' AND member. The member table has a reference to the 'contributor' table in the member table. But maybe I set this up wrong. It's the 'contributor' that should have a reference to the member table?

This is kinda database setup basics maybe.

What I would like to happen is that when a member upgrades to a 'contributor' there is a reference or connection updated and / or maintained in the member table.

So does that relationship have to be established explicitly in the function stack? or is that established automatically based on a field value creating the record in the 'contributor' table? Not sure if I'm overthinking this or underthinking it.

Appreciate the help