Hi. Without knowing a lot of the back story, where you are in what you are doing at this point in your life or what type of strained relationships you are referring to... .I can only add this.
My daughter recently got engaged. I like him - so that's not a bad thing. But my (now) exwife and her new family (she recycled me pretty quick and had babies with someone else)... .as well as her immediate family (my ex-inlaws) will probably ... .without a doubt... .be in attendance. And why not? I mean, my daugher practically grew up with my ex-wife as her mom... .and her immediate family as a family.
I'm not looking forward to it in the least bit. Talk about triggers!
But... .this day is for my daughter. I will be there for her and do whatever I have to do to make it a happy day for her.
(It sucks too... .cause I know I won't beable to partake in any celebratory drinks - cause god knows the triggers which will be popping off that day! I need to stay as focused as possible and 'fall apart' later if need be).
All that is to say this - this is a special day for your daughter (including the rehersal) - I would meditate for like 3 days straight before going... .get hypnosis... .block out unwanted people from my head or whatever it took to be there for my kid.
Hope that helps. Stay strong.