My fiancee's sister put in a petition for for my fiancee for a family member sponsored visa. They didn't know I was going to propose to my fiancee. Has anyone run across this or heard of it being a problem? I think I know how to handle it in the interview. I mean, she was just trying to be with me anyway.

Nothing to handle. A bit of a wait compared to a K1.

I often see that it is recommended that if you have several ways you put in for all of them. Not wishing to be morbid but if she wants anyway to move to the US and you are run over by the proverbial bus, she still has a horse running.