You can use the groups in Officevibe to replicate the hierarchy that you have within your organization. That way, you can have specific reports for your own company reality.
Create your subgroup
Type in the name of the subgroup you're looking to create. Just like if it was a group.
Add your subgroup
In the main/parent group, type in the title you gave to your subgroup. Just like if you were adding a member to a group.
You can go ahead and create as many layers of subgroups you'd like.