Hi Liz, You may not like my suggestion but try prong collars on the two loonies:-) Walk them individually when first using them and keep the leash loose, if they bounce off the leash they are going to correct themselves and the one time I needed absolute control my boy felt the collar once and never ever again. They looked like a lot of hardware but its rather like the curb bit on the horse rather than pull on a snaffle bit all the time it acutually is better for their necks than a choke chain. I doubt the Harness would work with a group of dogs, after all these are draft dogs and pulling on harness is natural:-) Halti's or Promise Collars may work but most of my dogs loathe them and despite my patience have thrown hissy fits with them, also if they forget themselves and launch after the demon car they could cause serious neck injury as their head would be jerked around in a twist. Your safety and paramount control comes first:-)
Rose T.
