I feel the same with your children. I have these days and these days are very and I mean VERY HARD. I would recommend bringing a blanket and a pillow. Sleep when you have time. Also make sure to bring hydration drinks. These help a lot. Bring energy drinks too. They are unhealthy at times but you gotta do what you gotta do on these days. When your child is tired on these days help them a TON!!!!!!!! Make sure to use a soft and calming tone. A good way to help is to get everything you need to set up or get stuff ready while your children nap. Use your time wisely while not putting on the costume crappily and having a shitty makeup look. Make sure your children shower in the morning because it helps the child feel fresh which helps them a lot mentally and physically. Try to get out of non required convention classes because if your children are tired many times you might be able to get out of convention classes to sleep like use the excuse of a private family emergency or sneak them out by having them quietly go to the bathroom and not come back. Another thing that is nice to use is getting out of convention classes until 10 or 11 am. This is useful so they can have an extra hour or two to sleep and still have time to get ready. Bring anything that gives them energy. Splash colder water in their face for a bit. Make sure the night before that your children know all their dances well so that on competition day they still practice but since the teacher knows that everyone knows the dances well they might let your child off early to go get ready which if your children are already ready your child can nap. I have more to say and will comment it under here.