I think you just have to remember that you aren't going to be able to cater to absolutely everybody. As long as you have things that the general population will eat, plus a few other things then you should be fine. You know what your Dad can and can't eat, plus pg women, so just go from there. I'm sure it will all be fine. Don't stress too much about it. One step at a time. Get the venue and get someone to do it and then discuss food....Good luck and i'm sure it will be a beautiful day anyways...