Maybe try less target shooting and more plinking? Milk bottles filled with water or the rotting fruit that shops give away are much more fun to shoot than unreactive paper targets.....failing that I would do some clay pigeon shooting, a little like golf and not easily perfected.
Another tip, get them shooting with kids their age, that might make it more interesting....

We've tried tin cans, and oranges and such...but the other kids idea might be a good one...maybe that'll get them over the hurdle of an hour's drive to the nearest spot where I can shoot a bit easier too...I wonder how much problems that I going to give me with the parents in the neighbourhood.

"MAAAAM, I just went with Rianne to the shooting range, and it was sooooo cool!
"To the WHAT?"
"The shooting range, mam, and Rianne's dad had the coolest gun, specially made smaller for...
"He had a WHAT?"
"A gun, mam, and we shot at..."
"Go to your roomm while I go have a talk with Rianne's dad, and there'll be no more of this gun business!!"

Yeah, I can that one coming from miles away...:-(

Frans