Your child always trumps your animal. This is first time you mentioned this in this thread. Euthanize the dog.
There's no aggression to children. There's not even sure aggression to other dogs - there's over excitement and mouthing, but OP herself said she wasn't sure if the dog was being aggressive or just doesn't know how control her pent up energy around other dogs.
I do agree that the child trumps the animal. I think that, if OP can't get a handle on it, sending it back to the shelter would be a viable option with the warning that he has to be in a single dog home. You see it ALL the time (I look for dogs I can't have more often than is good for me) - A dog will be up for adoption. It has the little checklist: Good with kids, cats, other dogs, etc. And sometimes, that "good with dogs" box is checked no, and in the description it'll say "Does not get along with other dogs, needs to be in a single dog home. This dog would be perfect for a family who lives on a farm out in the middle of the country and just wants one dog to help out with chores.
If the dog starts getting violent and aggressive - snapping, snarling, drawing blood - then yes, I would say euthing the dog is also a viable option, but so far her concern for her son is that he will get trampled while Oakley is trying to get to another dog. (having been trampled by my 200 pound dog plenty of times when I was younger, it's not as bad as it sounds). I do think if it's not fixed or the dog isn't moved to a single dog home it could escalate, but that's a whole other can of worms. I'm not saying that euthing is NOT an option.. Just, not the ONLY and IMMEDIATE option that she should jump to.
OP, you probably have... But have you tried working with Oakley while another dog is REALLLLY far away? So you can see it, but it's so far the dog doesn't mind? If that's an option, you could try working him on a leash with the dog far away, and SLOWLY inch it closer - close enough that he'll notice, but not close enough that he goes up the wall crazy. And then work with him some more until he ignores the other dog, and move him a bit closer... Etc.
Otherwise, look and see if there are any dog trainers who specifically specialize in this type of situation. If you can't get it under control, a nice remote farm might be the best option for him.