Can you combine travel credits from two Amex cards for use in one reservation?

Hi all,
say if you had both the explorer and platinum edge card, do you know if their travel credit add together?
Also, do you know if you need to use all the credit in one go?

They don’t add up and you have to do two separate bookings.
You could use one for airfare and another for a hotel or rental car for the same trip but a separate transaction