Believe me, I have expressed my concerns to her numerous times. Unfortunately, we tend to disagree a lot when it comes to the training of our animals in general (horses, dogs, cats), because she tends to be more lenient, while I want to be assertive (not mean at all!) and consistent. I will keep trying to talk with her though, and hopefully we can work something out.
Thanks for the advice. Maybe what I could do would be to let them eat for a few minutes before we go out, so that I'm sure they aren't as hungry. These horses do have pretty consistent access to grass though, so it's not like they'd be really hungry, like a horse who gets fed once a day might be. There are so many methods to consider, I'm glad I've got another couple of days before I really have to deal with this!