Heyy....well honestly I wouldnt worry that your sister has already stayed there...if its where you want to get married that I would only really worry about where you want to stay ...if you start trying to accomodate EVERYONE that you want to go than you will get frustrated and want to scrap the whole thing probably and thats not fair to you and your FI. So i say just stick with that resort and I am sure your sister will understand.