I'm sure your boy would get on fine with Jarrah, Serena. I am not saying that Archie will be good with other dogs but Jarrah is a clown, and Jarrah is a tart, and Jarrah would rather play than fight, so at least he has one more friend. She may help him settle down over at Obedience, we won't know till it starts up again next year.
The animals are nice and sheep are a lot smarter than you think. They're great fun except when things go wrong, and we've had a bad year unfortunately, losing a ewe, a couple of lambs, and having one lamb break its leg badly, and another get a torsion (twisted gut) twice. Those last two lambs are okay now but they certainly gave me a few more grey hairs.