Sounds as if she's a maternal kitty. Kitties, in my experience, will groom those they're fond of. Two of mine groom me, and one will take each of my fingers in his mouth and clean my nails (claws) for me, ever so gently.
And grooming the dogs is perfectly normal.
I guess you should watch out for hairballs with that amount of grooming.
I find it very dear.
P.S. Do you brush the other cat and her and the dogs regularly?