AITA for asking my brother to move my nieces christening ?

My fiancé and I are getting married at the end of October, my brother booked his daughters christening 3 weeks before our wedding. This has made my fiancé quite upset. She feels as though they are stealing the thunder of our wedding month. We sat down and spoke to my brother and his wife about changing the day of their christening. They claimed that between now and then there is only one weekend that works for them and the godparents. That weekend happened the be the weekend of my fiancé’s bachelorette party. They didn’t take that weekend because that would have meant my fiancé and my sister would not have been at the christening. My fiancé would have been fine with them having the Christening that weekend. They never asked if we were ok with them booking an an event the same month as our wedding. The sit down and asking them to change their date turned into a pretty heated argument between my fiancé and brother. My brother and his wife got very upset and we haven’t spoken since.