If you back tie the dog, have the helper move forward only when the dog is barking. Have a second leash on the dog attached to a prong collar and give little (tiny, small) pops on the leash with the prong. Small pops will enhance the drive and barking. These are not corrections, a prong can be used to build intensity and cause intense barking in this way. Since you have the second leash, you can control the dogs movement as well. If the dog starts to spin or jump the decoy backs up. When the dog is barking and focused the decoy moves in. This is how I would try it for a SchH dog, a police dog would be a little different.
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