Baby trouble

So me and my fiancé are getting married I a year crazy to think this time next year I will be a week away from saying I do. Along with getting to marry the man of my dreams I also get to gain two on the best bonus kids around they are great kids and I love them more then life itself. So we have talked about adding to our family and me and my

Fiancé one one more child but the kids are dead set against it anybody else had this issue and how did it work out