At the moment we have two groups, which are supposed to be 0-5yos (which I run & a parent must stay with child) and 5+ (parents need not stay)
I say supposed to as we do get quite a few 5 & 6 yos in our group as they have younger siblings & want to be together (or parent can't be in two places as child (or their parent!) not happy to be alone at the 5+ group)
We are basically a victim of our own success and at our last session had 37 children + parents (We started with 20 at our first session just over a year ago, and the numbers just keep growing, which is fab!)
The room we have available felt comfortable up to about 30 + parents, now it is feeling like mayhem. 
Our session is basically
opening song/prayers
story
craft activities
closing song/prayers (lasts about 50mins)
Coupled with this the leader of the older group would prefer it to be for 7+ so he can aim stuff at the older kids (they currently have about 20 in that group) I can see his point & the 5/6/7yos are generally more than happy in our group, it's just down to space/size of group that's the problem.
We don't have another room, so we can't split the groups down further.
I'm just hoping (and have been praying!) for some inspiration, as I can't see a workable way forward at the moment. Any suggestions/ideas/experiences would be very welcome.
Thank You :)