I seldom think about and remember that my FI's father is remarried. While he is remarried, his marriage is one of convenience, bringing her health insurance and him...well, I don't know. She lives hours away from him and us and I have never met her. He has girlfriends constantly -which she knows about and doesn't care about. They get together periodically and he cooks her dinner and they talk. My question is...do I invite this woman to our wedding? FI has never met her and wouldn't even think of inviting her. I doubt the FoG would bat an eye at her not being invited but...what is the etiquette on something like this? Should I at least put her (or a plus one for one of his "girlfriends?") on his invite?