Originally Posted by
applesauce
FNAs are applies in order of expiration. In your case to work around this you must book individual nights out of order.
Generally speaking, you make a dummy booking to temporarily "use" the first-expiring FNA to access the next-expiring FNA.
This is your answer. Book a dummy one further out for the first certificate, this way you use the 40k. Then cancel that reservation to get the 35k back. Now book using the 35k.
Its annoying but the easiest way to do it