I am located in SW PA. I have trained a number of kids and am a Girl Scout Program partner so I also have all the clearances necessary to work with kids. I do not teach a quick course. It is a minimum of 6 weeks once a week of around 4 hours split between classroom and pool.
The issue I see is with the younger ones. I would not have anyone else in the pool with the 13 and 10 yr old. With kids, 2 is the maximum I will have in the pool. You or your wife would need to be present of course, but they would be in the pool with me.
The two older ones can actually receive adult certs but they would be in their own sessions.
Also, depending on the level of maturity of the younger ones, there's no guarantee I would even start them. I'd need to interview them first and they would have to meet all the standards (agency and mine) without help from you to be certified. They'd need to set up their own gear, do all the classwork required, and demonstrate the ability to be self-sufficient underwater and be good buddies.
Some 10 yr olds can do this and others simply can't. Those who can't should not be certified.
I've worked with different instructors as I was coming up and all of the ones I respected taught this way. I saw a few kids get through one or two sessions and have enough difficulty that they were told to come back when they were older and their tuition was refunded.
I don't hesitate to do this. This is an extreme activity and the risk of serious injury and death is very real. In any class from a discover to basic open water and on up.
I would never sign up a child for a one or two-weekend cert with 10-12 hour days. That's just asking for frustration, injury, and worse. Even with exposure suits in a heated pool, kids will get cold and they will get tired. When that happens the learning and the fun stops.
They can also only absorb so much in the classroom and then they need a break. The younger they are the less time they can handle and retain the info.
I expect a 10 yr old to be able to answer the same questions as an adult. Also if that means more than 6 weeks that's what it will be. At no extra cost.
I provide training, I don't sell certs. Those need to be earned and in my opinion, it's more important that kids be trained as thoroughly as possible. In the event that something happens to the adult they are diving with.
I train them in the basic OW class to get control of a panicked diver, bring a non-responsive diver up from depth, do a rescue tow while loosening gear for extraction from the water, and support a diver at the surface and help them achieve positive buoyancy.
Again, 10YR OLDS CAN DO THIS IF THEY ARE PROPERLY TRAINED with the necessary amount of time. I've taught several in this manner.