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?