How do I create a hierarchy of UNIX groups as below?

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http://unix.stackexchange.com – I need to create a hierarchy of UNIX groups. Something like below: A |\ | \ B c |\ D e |\ f g ...where A, B and D are UNIX groups and c,e,f and g are UNIX accounts that are members of those specific groups. I have googled a lot but it seems that this is not possible. Currently, we have the following: Group A has members c. Group B has members e. Group D has members f,g. What I require is: Limit access to a directory only to members of group B (so B is group owner of that folder). But members of Group B needs to have the same rights as members of group A. Also members of group D (HowTos)