I own a very nice Appendix mare, Seattle. She takes heavily after her TB side in her confirmation and energy level. She is currently schooling 1st level movements, and some haunches in on a good day. There are two of us that are riding her consistently. I ride 2 to 4 times a week depending on my schedule. Another 17 year old girl (VERY good rider) rides Seattle about 3 to 5 times a week depending on her schedule.
My question is, how many riders are too many? I have the opportunity for another woman who is very talented to catch a few rides a week on Seattle. That would make three of us riding her every week. This woman rides through 3rd level, so really she would be more of a trainer than anything else for my horse. But would this be too much? What has been your experience with having multiples riders on a horse? And especially a TB that has seemingly unlimited energy? In your opinion, do you believe this would inhibit her moving upward in the levels more quickly?