how do i create a sub-group

Please help me to solve this problem: Organization A (a national organization)is a member of another organization B , organization A has sub- organizations (state branches- C,D,E) how can we create C, D, E under A and in turn under B?

You can check out the Sub Groups module https://www.boonex.com/m/sub-groups . It will only allow a Sub-Group to have one parent Group. I could further customize it to allow a Sub-Group to belong to multiple parent groups. Contact me if interested.