Alright wise ladies of the The Knot.. please assist me with your opinions and advice.In 2 weeks, my mom is hosting an engagement party for FI and I at her house. About 6 weeks ago, we each gave her short list of our close friends and family members we wanted to invite. I have a small family and only invited the closest of our family members, and the only friends who received invitations are the ones we will ask to be members of our wedding party.I want to re-iterate, SMALL. Mom wanted 30 people, MAX.Enter drama.FI is much closer with his mother's side of the family than his fathers (they are divorced, and his father remarried) so on his list was his mother, 2 aunts, 1 uncle and his grandparents (all on his mom's side). Also on his list was his father and stepmother, and that was it for family members. Well the stepmother called up my mother to RSVP today and left a voicemail mentioning that his father's side of the family hasn't received any invitations to the EP. When my mom called her back, stepmother informed my mother that since one whole side of FI's family got invited (the maternal side), then his father's side (AND her side!) all need to be invited as well. That's 18 extra people.Now my mom certainly didn't exclude anyone purposely, but this is a small gathering for close friends and family members, and the people that stepmother wants invited didn't even send FI a card for his birthday (which was today). These are not "close" family members. I can see her side, in the interest of fairness... but MY mother is hosting the party in HER house and MY mother is footing the bill, so my natural reaction is, "who the hell is this woman to boss around my poor momma?" EPs aren't necessary, she just wanted to have a little get together to celebrate! I'd also like to point out that this woman has not congratulated me on being engaged to her stepson and has never been overly warm and welcoming to me. My mom feels pushed around, I'm angry, FI is on my side, but no one wants to make waves or start a fight. Maybe it's not worth the fight, but it's still hella rude. What should we do?