FAB, let me also commend your Panhellenic spirit.
With only 55 returning members at a school where total is 160 and some chapters are around the 250 mark (

), allowing alums and actives from other chapters to help out with rush is only the right thing to do! They can pair up each alum with an active from Mizzou and have each pair rush 2 women during round 1.
I really don't understand why the big chapters are being such sticks in the mud... do they really thing that letting XYZ bring in some "outside help" so they have a shot at getting close to quota will really hurt their numbers all that much? Wow, they might end up with only 249 members!
I hope everything works out.