Feeding honey or sugar water to both hives you're combining with newspaper provides as a distraction and incentive and you'll have a much better take on the combination.
If you're using the supers next year you shouldn't have a huge problem with wax moths. I wouldn't even bother with PDB. If you should see any wax moth larvae no worries the bees will clean it up in the spring when you put the supers back. You'll only have major issues with wax moth if you're not...