I looked up the official terms and conditions of the Disney Rewards program. From item #10 under "Redemption of Reward Dollars":
"10. Reward Dollars have no cash or monetary value and may not be redeemed for cash or its
equivalent, and any unused portion (whether in your Card Account or transferred to your Redemption
Card) is not returnable as cash. If the Reward Dollars on your Redemption Card are greater than the
price of the item purchased, the remaining balance of Reward Dollars will remain on the Redemption
Card and can be used until they expire or are forfeited. No cash or other financial remuneration will
be returned to you on redemption of the Reward Dollars on a Redemption Card towards products
or merchandise whose price is less than the number of Reward Dollars on your Redemption Card.
Reward Dollars are not purchasable by cash, Disney Dollars, or any other form of monetary or
other payment. Redemption Cards may not be exchanged for or substituted with other rewards
certificates, rewards cards or Redemption Cards regardless of the number of Reward Dollars on the
Redemption Card or the expiration date."
I would read this to mean that you cannot transfer rewards on an expiring card to another rewards card. That has always been my understanding of how the rewards are handled, use it or lose it. I was surprised when someone stated that they were able to get rewards dollars transferred. So I wouldn't count on that being a possibility. Instead, use the rewards card to purchase Disney gift cards before it expires. That would be the safest bet.