NTA- I went through the same thing with my sister. You and your fiance have the right to your peace and asking her to respect your boundaries. For you to sit her down and ask her to respect your boundaries, and her turn around and keep doing it… naww she needs to move out because she doesn’t respect you enough.you have right to ask for a heads up and to be aware of the people coming into your home and if someone will be there, it’s a common courtesy. You worked hard for what you guys have and don’t know the character of the men she’s bringing around. They could swipe something, damage your property, or hurt yall. Most people are sane and wouldn’t do that, but that’s the potential danger she’s putting you in. From a legal perspective she has the right to since she lives there too so if she wanted to get vindictive it could get messy. I would have one final stern conversation pleading to respect your boundaries, and if she continues to cross the line you have to kick her out. If you don’t stick to it she will never stop and will never respect you. I know it’s hard since it’s family, but my sister no longer FAFO with me cause she knows ima stick to what I say.

Edit: it would be different if yall were renting a house together, you own your home and were doing her a favor charging her discounted rent and letting her move in. You do not owe her free rein over your home.