Our two dogs, one male, one female don't get along. What can we do?

My sister has a female bull terrier, Bella, who is about 1 year old. (I think she might be part something else because she doesn't much look like a bull terrier anymore and she is huge for a bull terrier.) My mom has a small, male, fox terrier, Petey, that is about 2 years old. Bella is VERY hyper and always wants to play. Petey just got neutered and is now very lazy. Petey bit Bella yesterday when my mom put them outside. We have 2 kennels for them inside but when Bella is in hers she barks constantly and whines. We have tried everything short of an electric collar. We don't want to have to chain them up in the backyard. We hate to have to alter them in the kennel all day. Is there anything we can do to make them get along?? It's driving my mom crazy! Also, Bella chews EVERYTHING. Including our house. We have replaced several window screens and the wooden plank at the back door. She's crazy! Please help! My mom is losing her mind over these dogs! haha.