Judging from the nature of the imposition, my guess is that until you are married this is bound to come up again. That being said, although I do think it merits a conversation with her about what makes you uncomfortable (her asking your chassan for money), I also believe you have to know your “customer”. There are some people who just have trouble hearing mussar, and it’s like talking to a brick wall. Is this someone who has personal insight? Furthermore, do you foresee her inappropriateness coming up in other ways post-wedding?? If so, it comes down to talking with her (if you think it will help) or distancing yourself from her.
Interestingly, when I read your second post of her “avairahs, I actually thought, in some ways, how lucky you are to have friends who “do too much” or fight over responsibilities. My mother had to call my close friends to help with things. They just weren’t the type to take charge.
The truth is, if your chassan is cool with it, I’d say “don’t sweat it too much”. He’s got to be a big boy and stand up for himself (and you need to let him) or after marriage you’re liable to maximize this role of protector of people taking advantage of your sweetie (and it may be fun for now, but it can grow tiresome and irritating if he doesn’t stand up for himself ). I’d let him practice this role now and try to adjust to his being a laid back personality.