Group under Group

Hey guys,

I'm very new in Drupal Development. I have a project in which I have to create a group under a group (not subgroup). Let me give an overview of that I want to do.
In a user profile page, he/she can create an project, this is where I want to create the top level group of that project. The group under the project group is the list of people(users) that are part of the project.
Summarily:Every project is part of a Group. In addition, every project has a group under it.
Anyone, have an idea how to do that?

Thanks!