Non-traditional guests

Ok so heres my question, I have children from a previous relationship and my kids asked me if I was gonna invite their nan (their dads mom) to the wedding. It's not that I have a issue with her, however I dont really want their half sister coming. She is a wild and I mean WILD child. They dont discipline her and I'm pretty sure shes never heard the word no in her life. Now dont get me wrong each child is special in their own way. They all need loved. However this child is one of the ones who constantly MUST be the center of attention. She whines when everything isnt her way and I dont want to deal with it on my special day. I dont EVER make things about myself I always put others first my children my fiance my family his family. So on the one hand I feel bad like I'm being selfish, but on the other hand I just want one day thats about me. What should I do?