Getting ready

I need help.
Back story I’ve been engaged for 6 months and over those 6 months my friends have been the only ones involved and helping me plan my wedding.
I have a mom, who I have a strained relationship with. And a step-mom who I have a decent relationship with, but her and my dad have had a lot of things going on in their lives recently so we haven’t really even talked about my wedding.Anyways, when I went dress shopping I took my mom and my step-mom (who do not like each other) and they made the whole experience… well not what I was wanting. I had planned on just getting ready with my friends the morning of, since they have been my main support since I’ve been planning. And have the parents come at a later time for them to see us. I really don’t want to deal with my mom and step-moms personal issues the morning of. Well today my step-mom texted me and asked if she could get her hair done with us in the bridal suite. Normally I would be okay with that but #1 I had already planned on it just being me and my friends #2 she hasn’t really been involved in my wedding so far #3 how could I tell her yes and not invite my mom. Which would lead to a even more stressful morning. And #4 my hairstylist is doing 4 peoples hair and has a time frame of 3 hours. I would feel bad adding on another person. I know this is a long post but I don’t know what to do or say to not hurt her feelings but also make it clear that it’s probably not the best idea.