[I would think if God "changed" me enough in heaven that my parents' eternal torment in Hell would not impact me anymore, that would be a form a mind control and loss of free will. I cannot imagine under any circumstances in which I would be ok with my parents suffering for all time.]

Sure, maybe it would be a form of mind control. But then you wouldn't know any better after it was done that way.

Think of it this way. In my human state I can hold out hope that God has a loophole to save the unsaved. That makes me happy now. However, after I die it turns out that there is no loophole and God simply rewrites my mind. I'm still happy because I'm ignorant of any loss.

Either way, God fulfills his word that there will be no more sadness in heaven.