Sub Groups

I'm new to elgg and I'm looking for features that meet my needs. I'm interested in the capability to have SubGroups. In my project, I presently have 12 basic Groups. Each group has at least one subgroup, some of them have dozens of subgroups. I would like participants to be members of at least one subgroup in one group, but possibly several. The groups and members of groups need to be easily identifiable. I've seen some very old discussions and plugins about subgroups but nothing current. Are there any solutions for this need?

Thanks, Doug