To be clear, there are two separate ways to redeem Membership Rewards points for air travel.

1) Points can be transferred to an airline frequent flyer program and redeemed for award tickets. The value of the points is determined by the frequent flyer program, not by the card used to make the transfer. In general, 1 MR point = 1 airline mile, but there are exceptions. Caution: award seats availability is limited. Do not transfer points until you have verified that award seats are available for the specific route and date that you need. Start here: Transfer Membership Rewards points to which airline or hotel program?

If your parents have frequent flyer miles in addition to the credit card points, bear in mind that most programs allow one-way tickets to be booked for half the mileage of a round trip. They could travel one direction on one airline, and return on another.

2) Points can be used to purchase airfare through Amex Travel. When you Pay with Points the full cost of the ticket is charged to your card, and then points are redeemed to offset the charge. Only if you have a Business Platinum card are 35% of the points refunded a few days later. Start here: https://www.flyertalk.com/forum/amer...35-2024-a.html