fmil wants to use her own makeup artist on my wedding day

I’m currently researching makeup artists for my wedding. My future mother-in-law informed me that she will be asking the makeup artist she hired 4 and half years ago for her daughter’s wedding to do her own on my wedding day. I will probably be going with a different artist for me and my MOH, MOB, and bridesmaids. She is graciously offering to book and pay for the room at the hotel for us to get ready in, so I don’t feel like I can ask her to have her makeup done privately. Would it be in poor taste for us to have our competing makeup artists in the same room? Do makeup artists usually have a problem with that? My sister-in-law is also going to be a bridesmaid, but I haven’t done the formal “bridesmaid proposal” yet. Should I be asking her if she’ll also want that other artist on my wedding day? My parents are paying for our bridesmaids makeup, so I don’t want to sign a contract and not be able to reduce the number of services later (I’ve read on most artists sites that you can add, but not take away after signing). Would it be bad etiquette anyway if she broke away from the rest of my bridesmaids to use the other artist? Sorry for the long-winded question! Thank you for any advice you can provide!