I have an idea about aircrafr order.
"Eligible" airlines may launch a public joint order with a certain amount of one type of aircraft, and others can participate the order.
With such order, carriers can get the aircrafts at a better price/leasing rate, and the discount is related to the total amount. but maybe they would wait longer because it takes time that the volume of the order is reached.
All the participant may pay, for example, 10% of the price/deposit ahead, and if cancelling, the 10% would not be refunded. The rest 90% would be paid when the order is formally acknowledged, which also helps airlines that don’t have enough cash to join the order in the first place. : )