Create release program is not releasing from the old open blanket purchase order. Why?

If there are 2 blankets purchase orders open at a time, Oracle will release off of the newest blanket, even if the old blanket still has a quantity available.

I would like the logic to be updated as follows:

1) If there is an old open blanket with a qty available, release from that blanket

2) If there is an old open blanket without a qty available, release from the new blanket

How can I achieve this functionality?