Core memory #1: Dad was always the one who had to use the key to turn the screw that led to the widening of my palate. Mom was both too grossed out and too soft-hearted for the process.
Core memory #2: the "key" (a small metal rod) that's used to turn the screw that opens the spreader (or whatever it's called) to widen my palate was on a string. Mom was further disturbed when she learned that was in case Dad fumbled it and dropped it into my mouth; the string helped with retrieval (spoiler alert: Dad never dropped the key once).
Core memory #3: the orthodontist said the process was painless...he lied. A little. It hurts when they attach the expander but that wears off. I was fine the first 4 months or so but during the last two, it hurt a little bit every time Dad used the key. But not a lot.
Best of luck to Jack...and to you and Mr. Kris who'll have to use the key.