all rewards are refundable more than 24 hours before the flight, minus a $55 per person cancellation fee.

if at least one flight on a reward booking is cancelled, or retimed more than 2 hours earlier/later, then you can have a full refund with no fees.

if these are two separate bookings, then you can have a full refund for the 3 hour change, but it would be standard terms for the 30 minute change.