Report of a user's membership in groove spaces?

I want to find out whether there is a way in Microsoft Groove to find out which spaces a user is in (and conversely which spaces the user is not in).

We run a free script called Personal Backup for Groove for our backups. The script dumps out all the groove spaces that our "backup user" is a member of. However, if someone creates a new space and doesn't invite the backup user, that space will never get backed up. We're trying to find a way to audit the "backup user" membership so that we can ensure that it's invited to all spaces.