a question about chickens

This is Matilda..poor thing is constantly picked on by the entire flock. When I say entire flock I mean the big girls and all the Bantys too.  We have separated her and tried to reintroduce her back to them, but again they jump on her, pull out feathers and tear her flesh up. Its like chicken cannibalism... Ick!

Senior and I are constructing a new coop for the bantys and roosters. But any ideas with Matilda? I feel so darn bad for her, but I need ideas on getting her back into the coop  everything we have tried fails. As much as I like her and even though she is a real sweety she can't live in a box on our porch forever.  
Any help and is greatly appreciated...