Bless you good man.
I hate that Amie and Carla are also working that day. They are two of my regulars. I know it sounds funny but I hate when I see a girl in the hallway of the spa that you regularly see but you are not there to see them that day. I know they could care less but I still would prefer having them not see me.
I hate that as well, but like you said, they could care less. If she does care, you can say you tried to book them but they were fully booked, or that the time you wanted was already taken. This game works both ways.