Sister (moh) bringing baby to no children wedding

Hi all,


My sister and her husband will both be in my wedding party, and their 7 year daughter old will be a flower girl. It will be a medium sized wedding (adults only, except the flower girl). The wedding is out of town, and with rehearsal, we will be there for two nights.
6 months in my engagement, after these plans have been established, my sister announces she’s pregnant with second child. I was\am SOOO excited. The baby will be 3 months old on wedding day, so a few weeks after the announcement, I asked what her plans were for the baby’s care during the wedding weekend. She insisted the baby would be coming to the wedding, and that’s all I got.
Whenever I try to politely get more information out of her, she gets offended. I know there will be family who can take care of the baby throughout the day, but am I out of line asking for specific plans? For example, my sister and I were going to get adjoining hotel rooms so there would be enough room for the bridal party to get ready; however, now with the baby, I’m not sure that’s an option.
My mom is very much empathetic towards my sister, and has made it explicit that my my sister’s wants and needs with the baby come first on this day…..so I have no one to turn to. I’ll also note that my mom is paying for a large portion of the wedding, so there’s that…
I really don’t want to come across as selfish, but I feel like my concerns are being pushed aside. I am willing to work in anyway I can with my sister to make this a smooth/fun day for her family, but she says she has it under control. Should I just let it go then?
I am a huge planner with anticipation anxiety, so not knowing how her baby is going to impact the wedding day/plans is stressing me out. I would just like to learn how others would handle this situation and if I am coming across as a bridezilla?