Getting groups and father group

Hi!!

In my process:

1. I need get the group name given a username (userId)

2. If I have the groupName I can get the Father group name, right?

3. If I have a father group name I can get the member of a group. right?

Well, I can't find the operations that I need for to do my algoritm to assign task.

Somebody can Help Me ?

Thanks a lot

María