Baby Name Trouble!

Hi! My sister and I are both pregnant. We are about a month and a half apart. I am due first. I always had baby girl names picked out, though over the years,my "favorites" have changed (as yours have too, I can imagine). I mentioned to one of my other sisters what the name I chose was and how fitting it was being so close to Easter. She adamantly said, "you know 'Kara' has been saying for years thats what she is naming her first daughter." She currently has 2 boys. If I DO choose another name, what if she never has her girl and the name that I've grown to love can be used? What should I do? Thanks for your tips in advance!