Limiting @mentions to groups

I feel like our issue has less to with groups and more to do with individual users and so these setting aren’t what we need here.

So essentially, we have multiple groups

As an example:
GROUP 1: USER A, USER B
GROUP 2: USER C, USER D

Now when USER A brings up the text window and writes @ they are going to see USER C and D. This is an issue because USER A isn’t able to communicate with C or D, or know if of their existence. They can’t see any of the discussions GROUP 2, so they shouldn’t be able to see that group’s users when they bring in mentions.

Does this make sense?

Appreciate your help.