This is one of the very important and under covered issues with FAA regulations. The Oxygen requirement rules from the FAA only applies to (1) HEALTHY (2) ADULTS. When going up, you are not sure what is the proper altitude that your kids lungs surface area is going to compensate for lake of oxygen. Adding the fact that they are sleeping and their respiratory center already inhibited and under control of autonomous nervous system only. If those were my kids or grandchildren I would (1) carry oxygen, (2) monitor oxygen saturation using reliable finger oximeter every 10-15 minutes, and (3) apply oxygen mask if O2 saturation dropped below 93% (very conservative). You don’t want to expose those young developing brains to hypoxia. Another aspect missed in the FAA regulations is the rules applies to adults with lung diseases as COPD, pneumonia or even pleural effusion. I would follow the same rules above. Please note that those are my rules that I feel comfortable applying them. Thank you Mohamed