You may want to go ahead and just bathe them. It's really simple! You just run some lukewarm water in a sink, dunk them under gently, keeping their head above the water, lather them up with some baby shampoo and rinse them VERY WELL. I use a soft-bristle toothbrush (one of those cheap ones from the dollar store that come in 4-5 packs) to clean the tails of my rats because of the hairs.. Just wiping doesn't always get it perfectly clean.
Good luck with your girls!