My neice had a High Mass Catholic wedding, I've been to alot of Catholic weddings, but this kind........oh my gosh, 2 hours......not my thing. My daughter is getting married in April, it will be a nice wedding that at the longest will 30 minutes. The guest book is very easy, you just stand there and the guest know what to do. If not just ask them to sign the guest book. You can do this for your sister, just remember you may end up getting married yourself one day, my sisters didn't cooperate much at my wedding, I would have liked to have had more pleasant memories of that day, please......just do this for her, it's just one day.