Because your kitties have each other you probably won't have much trouble. My experience is below. Hope it helps.
When my dog passed away my kitty Knug was so depressed. He barely ate, stopped playing, did not use the litter box, stopped seeking attention and snuggling, and doubled the amount...
My 7 month old female kitten, Damage, started this behavior a couple weeks ago. On the bed, on carpet, on the hardwood floor, doesn't matter to her. She goes through all the motions of digging a hole. There must be some sort of instinctive behavior associated with it. I just don't know what it...
