HELP!!!! Middle name for our baby girl!!!!!

So long story short, I'm due in April with our second child which is going to be a baby girl! We have a first name picked out but can't decide on a middle name! My husband wants to name her after his Mamaw who raised him which I'm perfectly fine with. Her name is Catherine James and I love the name Catherine but my husbands sister who we both don't get along with due to personal issues was named after her as well and I don't want her to go around saying we named our daughter after her and not His Mamaw. I have talked to my husband about it and he also agrees that it's too much alike. We are naming our daughter Maelynn just like it's spelled and his sister is Mary Katherine. We thought about doing Maelynn Caye but I still feel like it's too much alike. What do you think? We want something different and not alike! Please help!!!!