CDTraveler thank you for the advice. They most certainly are on ketogenic diets, and it is my friends biggest worry. Their seizures are pretty well controlled, no grand mal, with medications and diet, but the family is also at a point where seizures aren't an emergency. They don't run to the hospital even for GM seizures, they medicate and treat and call the neurologist. Generally they are caused by diet getting messed up (it is really hard with kids!) so sticking to their diet on the trip is extremely important to avoid seizures on the plane.
It would be hard to see their list of medications and diet needs and no realize that they have seizure disorders though. We also had to list each medication by name, especially the liquid ones, in our clearance letters when we flew with my tube fed, oxygen dependent child. They almost took away our hand sanitizer because it wasn't specifically listed in our letters. If the MCT oil isn't specifically listed, won't they run the risk of it being confiscated? That would be disastrous.
Thank you so much for the tips and things to think about!!