Limit MSI install for specific users then add more?

Hello all- I am attempting to slowly introduce SFDC users' access to MSI from about 6 to 30 people, a few with different profiles, over a span of time. 

I have read quite a bit  that there isn't an easy way to police MSI frame visibility in situations like this, and have seen a few options that recommend dedicated profiles and/or permission sets to constrain.

I am wondering if anyone has a good solution for this?

If I choose the option when installing the MSI package called "Install for specific users", can first install for 6 people (different profiles) and then later add additional specific users in a fairly straightforward way somewhere? Would additional install require an override of some sort?

Any info appreciated.

Thanks,

Aimee