The only thing is--Standardbreds often trot AND pace naturally from birth. They often trot when turned out. When they are racing they are trained to not break from a pace--but the trot is still there. When they are taken from the track they can be encouraged to trot, and they will learn that it is okay to trot. Sometimes they have to be ridden in a bitless bridle, because use of a but may be reminding them that they are supposed to pace. Sometimes it is a matter of keeping them relaxed, then they trot--if they get anxious they revert to pacing. It depends on the horse. But--the thing is in the Standardbreds the trot is there.
If this Mini always paces and especially if she is pacing even when turned out and she is in the company of one or more diagonally gaited horses--then it seems unlikely that anyone will be successful in getting her to trot.
I once knew someone that raised Walking Ponies--Tennessee Walkers crossed on...Welsh ponies I think it was?...and they were gaited like the TWH. The breeder said, though, that he had to be sure not to turn them out with trotting horses. If they were out in a group of trotting horses they were likely to abandon their lateral gait and take to trotting instead. If this mare is out with trotting horses and still paces and never trots then it seems the pace is very strong in her.
