What I did (it's been hot enough that I haven't played as much as I want) is I bought a horse with a lot of easy going traits to be my sims' "Learn to Ride" horse. He's mellow, friendly, and I forgot the third trait, but it was also a positive.
Then I rescued a foal, which my child sim is doing most of the primary care for, which will be hers.
My over all plan is to get everyone decent to good at horseback riding, and then focus on rescuing and "rehabilitiating" horses. (read: training up their temperment) Yes, I'll be selling them again, but I can decide that for story purposes, they're going to a good home. But those first two horses will stay.
