change of ship-to party right before dispatch on delivery (not order)

have a client that consistently has to change the ship-to party right before dispatch. the client has customers that are dealers, who in turn have sub-dealers. the dealers very rarely accept shipment to their address, they want the delivery posted to the sub-dealers and this can change at the last minute. as of right now, the addresses for sub-dealers is not maintained by the client, but they would like to have this option.

i would like to maintain the address of the sub-dealers. but once the delivery document is created the ship-to party is greyed out, how would i change this, so i can enter a new ship-to party? the address changes last minute, but after the delivery has been created.

thanks in advance!