Originally Posted by
deltame
If you have to pay $1K then pay it because extra time with your grandmother appears important to you; however please also consider whether its cheaper to book a new one-way ticket to HKG -- I just searched ua.com and found a $820 all-in for Oct 5th 12:20pm departure IAD-NRT-HKG, code share flights operated by NH and JL respectively. You might want search for fares from other airlines too. Safe travels.
OP is departing IAH not IAD, the only option that depart IAH at a later time to HKG is a 10:50am which one way cost $1600.