Manging groups

I have groups with 100+ users currently in them. I need to remove all except 10 or so users from each group. The easy way to do this would be to open the group, multi-select the 90 or so users I need to remove and simply remove them. (5 minutes)

But this is not possible in JIRA

I need to open 90+ users one by one and remove them from the groups. (Minimum 1 hour)

Are there any plans to improve group managability? The ability to add a group to a group would be very usefull too.