Forced to have the best friend of my future sister in law as a bridesmaid

Well put, Valerie!!

This situation is interesting. I don't like how your fiance APPROACHED you about it. He says that his sister's best friend HAS to be a bridesmaid. No. Absolutely not. Now, in my opinion, you both are a unit, you are one. So, though he's the groom, I think there is nothing wrong with him voicing his opinion, and getting your take on the situation, but I think it's entirely wrong that he is telling his future wife who WILL be a bridesmaid, rather than getting your take on it. I think having FSIL as a bridesmaid is not too bad, although it's definitely not mandatory at all. You both are getting married and you both should voice opinions, not determine for the other what will take place. Always give your input, and listen to the other person. That's the best way to do it. I agree with how you're feeling about the situation. If my FH told me that one of his groomsmen wants his sister to be my bridesmaid, I would immediately decline and wouldn't give it another thought. It's self explanatory why I'd say no in that situation. I would never choose someone to be my bridesmaid and I know NOTHING about this person. Furthermore, agreeing with Valerie 100%, a bridesmaid's "duties" aren't really mandatory at all. They don't have to plan you any parties, or even attend them. I know, I get where you're coming from. But, yeah it's not at all a job. I have my 3 sisters and 2 FSILs being my bridesmaids and I expect nothing of them except for them to acquire their dresses and do their hair (might provide makeup for them). I do not except them or my MOH to throw me any sort of party! I know though, every culture is different, so I respect that. Bottom line, speak with your FH and tell him that while you understand this little friend is like a little sister to him, you don't really feel comfortable with making her a bridesmaid. Perhaps she can have a different role? A little usher? Giving out wedding programs and stuff like that? Can she sing? Maybe she can sing during your reception? And see if you can compromise with him. All the best!!!!