Have you tried to put their litter box outside? I read about that trick from several like situations, never tried myself (thank the gods, never needed to).. Especially in quieter times, like maybe at night?
And look carefully around the house too - sometimes they can be VERY near, but scared and so hiding. A friend of my mother found her cat after days right next to her place - hiding under the garbage bin!
Actually... look thouroughly IN the house. Moving is very stressful for cats, and they can even be hiding there : a neighbor found her cat behind the washing machine, after looking for a couple of days.... so unless you KNOW for SURE that they left, it's worth a try too.
I am not sure if the cats would know how to go back to your previous home? Ask the neighbors/friends there to keep an eye out.
And posters/leaflets...
I hope you get better, and that they return to you well. The rest will be sorted, sooner or later.