Credential setup so that each user uses their own credentials for shared hosts

We are deploying RDM.
I have 12 different corporate sites
I have 12 unique users and permissions per site. We do not share credentials per site
Each site has 100 hosts each est.
We are using Enterprise version of RDM and use the same db on azure.
We all have unique user permissions to the RDM db.

I want to set up the hosts in a way that each unique User uses their own given credentials per site.
I will put each site into a Group folder
I will set the hosts to Inherit credentials from the Group
I am hoping this will save time in the setup process and future changes, in that each person doesn't have to to go each Host in each Group and set up credentials.

However,

As I set my credentials to my Group I over right the credentials of the rest of my Team, because will I update the db with my changes.
How can I uniquely set my credentials to a Group that does no over write my Team members credentials?
I would expect my Team members to set their Credentials per Group on their own.

Thanks