My (40f) daughter Raquel (15) and niece Janelle (15) share a birthday. They are very close so my brother Mark and SIL Yasmin have been working with me and my husband John for the last six months to plan their birthday party. We talked with the girls to see what theme they wanted and they both wanted a formal party. For the color scheme they choose black, gold and white. They also told us that they wanted everyone to wear black, gold or white to the party. No other colors. This worked for us and we started planning their birthday party.

Since we have been planning six months in advance we told everyone the theme and dress code for their birthday party. So everyone knew what the dress code was.

The party is this Saturday so my oldest brother Jeff decided to come over and talk about the party. He has a daughter Melanie (14) with his wife Penelope. He came over while my daughter was out and we started talking about the party. He told me that Melanie was very excited for the girls to see her dress and asked if he could show me a picture of it. I agreed and was very excited until I saw it. The dress was a floor length sparkly pink dress that was beautiful but it didn't fit the theme. I told him that and he kind of got mad at me saying that he couldn't just buy her another dress and told me to tell the girls to make an exception for his daughter. I said that wouldn't work since the party was already planned. He told me to just think about it.

When Raquel got home I showed her Melanie's dress and said that this was what she wanted to wear to the party. Raquel said that Melanie's was beautiful but it went against the dress code, so I told her that Jeff can't buy Melanie another dress for the party. Raquel said that Melanie could borrow one of the dresses she had because she wasn't exactly sure which dress she wanted to wear. I went and told Jeff this, who called Melanie and told her what Raquel said. Melanie flipped out and screamed that she just wanted to wear the dress that she brought because she loved it. I told her that her parents knew about the dress code and should have told her when they were shopping for dresses. Jeff got mad at me again and demanded that I tell Raquel to change the party. I shut that down because the party was already planned and the theme, color scheme and dress code have already been decided. I told him that if this was such a problem they didn't have to go. Jeff got mad and left to go home.

An hour passed and my mom called me to tell me that I was wrong to ban Jeff and Melanie from the party. I told her that they were only banned if they couldn't follow the dress code Raquel and Janelle came up with. My mom said that shouldn't matter and family should always come first no matter what. I agreed and told her that my daughter and niece come first since this is their party. Again if anyone has a problem they don't have to come. She hung up and I didn't hear from her for the rest of the day.

Today my SIL added Mark and I to a group chat to tell us that Melanie felt like the girls were ganging up on her by enforcing the dress code. I replied back and said that they weren't ganging up on her this was a rule for everyone invited to the party. This made SIL mad and she told us that we were jerks for making a little girl feel bad about a dress she likes. I told her that it wasn't like that but she blocked me so it didn't go through. So now I'm here asking if I'm the a-hole for sticking to the dress code for my daughter and niece's birthday party?