How to become an Admin of a group where the creator/admin is not active

I am a member of a group that shares recipes, tips and chats. The creator of the group is not active at all. I can get hold of her. We are a few group members who want to stream line the discussions board of this group but are unable to do anything. How can 3/4 of us become admins so that we can delete old topics on the Discussions that have been saved to new topics?

You cannot take over a group on Facebook, no matter how active its admin is.