I not sure if this will help you or not but I'll give it a shot. Is he food motivated? Does he enjoy playing with a particular toy? If so then you could help him associate being out with you as a good thing by giving him a taste of wet food or a treat. If he prefers play, then find that special toy and start playing with him while he's out with you. Maybe over time he'll begin to then enjoy being out with you and your family. Good luck.