OP please don't take offense to this, I really am just trying to help, but I really don't think that this barn is the best place for you, your friend, or your mother. Your riding instructor may know what he
is doing as in he is an excellent rider and knows his way around horses but from what I have read (again not trying to bash him you have just given us very little information on him other than not
to bash him) he doesn't know how to teach it to others. I help give lessons to beginners and work as a riding instructor at a summer camp. At every lesson I have ever taught the horse is assigned to the rider. It isn't because I don't think that the rider is unable to pick a horse they "click" with, it is because the horse they "click" with may not be the appropriate horse for them. Horses each have their own personalities and quirks and as an instructor it is important to know each and every one of those quirks and match them to a rider that can
A.) Not be scared by said quirk and gain confidence
B.) Learn from said quirk and become a better rider because of it
It concearns me that your instructor lets you pick your own horses, because I know if I let my
beginners pick their own horses they would all end up on horses that are too challenging for them or too easy for them. Sure they might "click" personality-wise, but they probably won't match up skill wise.
Now I am not trying to say your instructor is a bad guy maybe he just didn't evaluate everyone's ability correctly. I will admit that I have done that before and have had to talk with my students about how they feel about their riding abilities and who they feel they would be more comfortable on. Have you talked to your instructor about your insecurities? When it comes to being insecure or nervous or whatever you are feeling during a lesson you should always be able to go to your instructor, that is what they are there for
Try talking to him with your friend about the horses that you guys ride, maybe he will have a different solution or tell you why you should
stick with your original horses, or maybe he will tell you it is a good idea to switch, maybe he will even put you on different horses completely! Whatever he choses you should feel comforted and better about yourselves, your riding, and the progress you will make. If he doesn't listen (which I am not saying he won't) I think it is time to find another place to take lessons.
Good luck with whatever you choose and let me know if I was helpful at all! And again please don't feel attacked by my post, I am jst trying to help you with your situation from what I have read