Once the pups mature and gain some stature / size, they can hold their own vs. Jackson and sort things out themselves. Who knows, one of THEM may be more dominant than he is.

The thing for now is to protect them and let them enjoy their puppyhood, without Jackson hurting them.

What about the breeder where you got the 3? Any insight from that person?

I think crate training the puppies may be a good thing for a start, just so Jackson can't hurt them.

Or, do you have a doggie door, or does Jackson stay in the back yard while you are at work? I there is no doggie door, can you gate off the kitchen and leave the puppies there for a week or so? Put down some paper or pee pads. They will be out of his way, and still able to do their puppy thing. This won't work for lon, as I recall BC's can jump and any gate will just be a challenge for them to conquer, he hee.