I have 2 new users who need limited access to CRM because they are contractors. We've never had contractors in the system before and the permissions are getting a bit confusing for our use case.

Both new users support the same 5 Customers, so they should have access to all 5 Customers, as well as all Related List records affiliated with those Customers (Deals, Contacts, Custom Modules, etc)

They should both be considered the "Owner" of these records, or at least both be able to access & edit all the same records.

Is there a way to assign permission based on conditions? (eg. If Customer Name = X, Y, or Z, give access to User1 & User2)

Or even a way to assign a Group as the Owner of these records? (eg. Group containing User1 & User2, and every record related to these 5 Customers would be assigned to that Group)

Open to any other solutions as well.