How can I win over my fiance's oldest daughter?

I am 50 and my fiance is 47. All of his children like me, except his oldest daughter, 29. She calls me his "va-jay-jay toy." She is married and is about to have her first child, his first grandchild. The baby shower is this Saturday, and the whole family is flying in from all over. She has made it very clear that I am uninvited and that if I show up I will be shown the door. I am hurt about being left out of this family gathering, but I would never make my fiance choose between me and his child and grandchild. She, however, has no compunction about doing so with vehemence and malice that makes me wonder if something else is simmering below the surface that has nothing to do with me as it has to do with what I represent to her. I met her and my fiance at my fiance's father's funeral. I was very close friends with his father, whom the daughter had never met. My friend was estranged from his family; no one, including myself, knew why he had chosen to keep them at arm's length, he would never talk about it, but I immediately bonded with all of them. After the funeral she gave me a ride to the train station at the request of her father and she seemed to like me just fine. She is a Jehovah's Witness; we talked about God and spirituality and we seemed to connect on that subject. She invited me to attend a convention that coming weekend, which I did not attend (I am Roman Catholic and so is my fiance). After I hooked up with my fiance, I attempted to "friend" her on Facebook and sent her a total of three messages over the past year, telling her I'd like to be friends, congratulations on the upcoming happy event, her grandfather would have been so proud. I never received a reply to any of my messages, and thought maybe she didn't remember who I was, so I stopped writing and left it alone, figuring it'd be better to get to know her better in person if and when the opportunity presented itself. In the meantime, I started dating her father, which we kept quiet until about two months ago. He is the most wonderful man I have ever met, and he loves all of his children very much. The three youngest children live at home with him, two boys aged 21 and 16, and a girl age 12. I have never been married and have no children and I am very much looking forward to being a wife and mother. He went to visit his oldest daughter around the time that our relationship became known to others. She had posted pictures of her ultrasounds on her Facebook page and in my third message I mentioned that I was following the baby's progress. The next time I saw my fiance after he visited her, he told me, to my dismay and surprise, that she thinks I am stalking her and she thinks I am psycho. It turns out that she is close friends with his ex-wife and regards me as an unwelcome interloper. I know that it is going to take time to get to know her, and I realize that she may never like me or change the way she feels about me, but I don't want to give up trying. Can anyone give me some pointers about how I can break the ice and get her to at least give me a chance?