Because I'm amazing. Lol jokes, no I think it'd be a great opportunity to co own a group, I never have done so, so it would be a real decent thing if I were! I will help increase the activity of the group, trying to hit that 1k posts as long as you help also.
What I would do?
I would post constantly in the subforum, and make sure people are posting their correct amount to stay in the actual group without getting kicked. I would also host exclusive giveaways to the group, for example the 110th post for a nice snapchat or something, like @ghost himself had done with a stat instagram.