Inclusion of Stepdaughter

Hi!
Okay, my Fiancé and I have been together for 7 years, come October 1.
We met when his daughter was 14, his son 16, and my son 13. I was Not the woman right after their mom. I am 12yrs younger than he( or his ex-wife) is. I model professionally, we were a blind-date & he moved me in very quickly.
From 6 months into the relationship his daughter had it out for me. At 14 1/2 she said "I'm going to do whatever I can to ruin this relationship- because of all the hell dad put me and my brother through with the woman before you."
And, DAMN!, she tried! Telling him I said things I never did. Saying I pushed her down the stairs when she fell down them- thank God her older brother Saw her fall and told their dad she was laying! Or telling him I was seeing someone else- but little did she know I was actually WITH Her Dad! The worst part is that he wouldn't put a foot down on her disrespectful, abusive, attitude. Until June 24, 2018 that is, despite her causing a scene in the restaurant 2 days before we left( I wasn't there, but he told me) about him telling them he was going to propose, he still did propose...
We went to Ireland for my 40th Birthday and he proposed while we were there- what a wonderful birthday gift!
Her, female, cousins & friend and I get along Very well. So well, in fact, that one of her cousins I've asked to be a Bridesmaid.
So, now that you have the back story, here are my questions:
1) DO I HAVE TO INCLUDE HER IN THE WEDDING PARTY???
2) DO I HAVE TO NOT INCLUDE HER COUSIN?
3) Do I HAVE TO include Stepdaughter IF I include her cousin??
( She told her boyfriend, when she saw the wedding planner on the table, "I'm going to call and cancel whatever she does!"and other venomous things. So I'm not inclined to Want her in it!
And FYI: I had always wanted a daughter. Doing the whole makeup/hair/nails thing.... So I went into this as a Friend, or cool aunt, NOT a mom figure!)