Have a DP about double-dipping on the Hilton Aspire's old "$250 annual Airline Fee credits" with the new "$50 quarterly airline credit" (which can be used on any airline, and don't need to be on fees). I was trying to use up my unusued $250 old airline fee credits on Jetblue, and triggered both the old and the new credits on the same transactions

10/19 - Made 3 purchases of flights with Jetblue at $73.90, $73.90 and $108.90 (which total a little over $250)
10/24 - I saw the meter change on the new $50 credit (no visibility to old $250 meter)
10/25 - Credits posted with an "as of" date of 10/23, but there were 4 credits. The first 3 were in the amount of $73.90, $73.90 and $102.20 (totaling exactly $250.00 for the old credit), and the 4th credit is in the amount of $50 in the new credit.

So, the old $250 credit seems to still work as advertised through 12/31. And, you can simultaneously trigger the new $50 quarterly credit on the same transactions.