OK, so I am pretty new to SharePoint but here is the thought!
I have determined several metrics such as location, BU/dept, Function etc.
Each user must belong to one or more Groups based on a metric. The site allows access based on metrics. I want to limit a site to members of Metric 1 + Metric 2 only without creating a new Group. There will be a huge number of permeatations required to define every possible group.
So, is it possible to provide access based on memberships of groups where the user must belong to Group 1 AND Group 2?
E.g. Member of New York(G1) and Managers(G2) - must belong to both, not either!