Get some heat pads to put
Under the carriers to make sure they are warm. Put snuggle sacks that smell like them in the carriers, for them to sleep in but also keep familar smells.
I'm assuming you have suitable holiday cages for them both ?? Keep familar smells in there, maybe some of their old bedding depending what bedding you have. Familiar toys ect.
They should be fine, as long as you keep everything relaxed, keep them warm, keep familiar smells, and take familar things with you for their cages.