Apart from knowing the kids and how they'd be riding your horse, you should also be sure whether your horse is suitable for it. My horse used to be a lesson horse for a short time and he absolutely hated it - tried biting the trainer in walk lessons, avoided cues, tried bucking in beginner canter lessons and was generally a trouble. Ever since he's mine, he's a whole different horse - light, responsive, attentive. All that just because he hated all those hard legs and hands of kids.
I have come a long way, to surrender my shadow to the shadow of my horse.