New Chicken in Existing Coop

We have recently got new neighbours who have a springer spaniel. On Saturday prior to letting the girls out we were in the garden and the dog came straight through the fence (which is rotten I admit!) and into the garden! We put a double layer of chicken netting all round the garden. Unfortunately yesterday, we had to go out in the morning and when we got back we had 1 chicken and a pile of feathers and the netting all down plus a dead squirrel in the garden.
We looked everywhere for the chicken but no luck so presumed the worst and have arrange for a new chicken to arrive on Friday to avoid the remainder being lonely.
Last night we decided to have a chat with the new neighbours and they confirmed that the dog had brought the chicken into their house but it was alive when they let it out into the garden. After a great deal of searching we eventually found her in a tree (Bantam leghorns) and we brought her back and put her into the coop.
Not sure how she will fair after the ordeal and now wondering how we are going to integrate the new girl into the coop - any tips as to how we make this work?
The fencing is being replaced this weekend!
   

Thanks for your help. The chicken is getting loads of tlc and is looking and acting OK after her ordeal. We are going to see the farmer today and hopefully put off the new arrival!