Everyone trying to use Sub Groups for organizing their environment in STM will recognize that they have been used for a certain backup feature not even supported in current version of STM (5.7).
So currently there can be one group level and the group automatically appears in every section where corresponding content is assigned to it.
Maybe it would be more valuable to be able to create a free group hierarchy and so also get very customized summary views for that groups.
e.g. with a parent group per physical location (city, region, ....) and different sub groups per location for e.g. for different department related equipment/volumes/luns....
Or a customized Tree which represents the implementation more logical / human readable e.g. with Storage system on top per site, then below e.g. LUNs per site and one level below VMs related to that LUNs or however the setup may look.