Pollypuss2,
You have several issues that you need to work on. On the tissue thing. You can try spraying Bitter Apple on some tissues and when the dog takes them he will immediately want to spit it out due to the bitter taste. Saturate the tissue so the taste is really potent then let it dry before having it placed in a place the dog may try to steal it from. You may use a mild form of hot sauce if you don't have bitter apple. Make sure there is plenty of water for the dog available afterwards.

Young children are going to be a little more difficult. Basically because you can control your dogs reaction but not small children. When an excited, squealing child rushes up to a dog to pet it, the intense stimulation can trigger a chase or defensive response that could lead to a nip.

Controlling your dogs response is done by slowly introducing your dog to small children on purpose. Take him to a park and always have him on a leash. From a safe distance from any children playing you can reward the dog for calm behavior. When he looks towards the children give him a treat. Only when he looks towards the child. Move closer when you think it is okay. Repeat the procedure. Make sure the dogs ears are not back or hair standing or fidgety behavior is being shown and reward every time the dog looks towards the kids.

Keep moving closer till eventually you are really close to the kids. If they ask to pet the dog tell them no you are training. At a time when you feel the dog is calm and ready have a child you have preselected try to pet the dog. This child should be told how to approch the dog ahead of time and how to pet it. Most kids pet from the top down and they do it quickly, which violates the dog's concept of secure personal space. Teach them to pet from below the pooch's head. Extend a hand and let the dog smell the hand first. Have the child go slowly. You will have the dog by the leash and rapidly reward for good calm behavior. This is teaching the dog that when children are around I get treats. This isn't so bad after all. You are basically starting at the ground and socializing your dog to children.

It will take some time but a few weeks to a month are worth the fact that you won't have to worry as much around small children when your done.