The bearded collie is a wonderful family pet that is good around children. He is a people dog for sure, and loves being around his human family. He is a good indoor dog whether he's a worker or family pet. He loves to play, so the children can definitely help keep him occupied for some time playing with him indoors or outside in his exercise area. In fact, children love playing with dogs more than adults do in many cases. After all, what do children do best? It's in their nature to play, and playing with the family dog is part of that.
Since you already know your bearded collie needs a great deal of exercise, and he is so good with the children, allow the children to participate in as much of his exercise they are willing to do. Your dog will be very responsive to any kind of play, and as long as you keep him entertained, he will stay out of mischief. You don't have to worry about the bearded collie harming your children as long as they don't agitate him. Like any dog, they will become frustrated if agitated, but in all likelihood, he will walk away like many other breeds of family dogs.
Bearded collies are also good with other family pets, especially those that were in the house before you brought him home. Of course, simply because your dog doesn't have a problem with other pets in the house doesn't mean they won't have a problem with him. It's important to make sure your other pets understand the presence of another animal and do not attempt to attack or provoke your bearded collie. He is not an aggressive dog but one who is capable of getting along with other animals even playful, especially as a puppy.
Before you bring your new dog home, you want to make sure your children understand the importance of not overdoing it and allowing the new dog to fit into the new surroundings. This is true not just of bearded collies but any dog breed. They need to feel comfortable with their surroundings before they will be willing to play with children or other pets in the house. This is easier and more quickly accomplished if the children don't pounce on him when you bring him in the door. You may want to confine the other pets until he is able to take the time to check them out on his own. Even puppies are frightened until they discover they are in a safe place, which may take several hours or several days. Allow him to become comfortable with his surroundings before you attempt to introduce him to young children and other pets.