So, we are being philosophical.
Using your criteria, how large must the "group" be? Two? More?
Use of the word "group" gives me the impression that you discriminate against the individual? Must be a Statist!
Also, is there a specific area requirement?
I feel like a stranger in a strange land!
Because this is a new question, the answers have not been decided. Therefore I can’t give an answer to your quetions about how many etc.
But nevertheless the practical questions must be answered definatively in time.