you would need to clarify a few things first.
1) How far in advance are you cooking the birds? Typically I try to have the chix finished just before I have to leave for the event to prevent them from drying out and having to quickly get them back up to temp...
2) How long will it take for you to get to the event?
3) How are you transporting the food? If using a Cambro pan carrier, the temp will hold for up to 4 hours (as long as you prep the carrier first). Also plastic wrap over the pan followed by foil will keep the heat in therefor "steaming" it, only issue is if they are wrapped like that for too long you will risk too much condensation in the pan.
4) Are you saucing before you leave or at the event?