Superior Flight in RYY Kennesaw is where I'm at. The school is transitioning right now to focus on part 141 full time students, but I've been told will have still have part 61 available come January. (Joe sold the business last year). Website for example is down right now as they transition.
I can't speak to the ground school, as I came in with the written already done. I believe the ground school that they would offer for part 61 would be one on one with your CFI.
If the boys are out of school, call Will at Superior and ask what they offer. If the boys are high school, have them work the written test using Kings or something on line IMHO. But I'd at least have the boys take a discover flight and see if they actually like flying.