Thanks for all the advice.
RE: the test
It was $60 for the test plus the vet consultation fee. She said she was drawing blood for the test but they took him to another room, so not 100% sure. It is a residential avian vet though, as we live in the city I do not have access to a farm vet. I know the test can't be 100% conclusive however when I asked her she said the results would be pretty accurate. I am mostly looking at the test as another piece of information about what it may or may not be. So now I know:
- test indicates probably not mareks
- not one chicken lost
- recovered with administration of vitamins
- no symptoms in adult flock mates
RE: their recovery
The two roos did go down the hardest, the one that I had isolated slowly recovered over about a week to where he could stand. At first he couldn't stand at all, but with additional vitamins, he began to be able to stand if you helped him get up, at first for just 5 minutes, then the next day 15-30, then the next day he'd walk around until he sat down, at which point he just needed help to stand again. He started sitting down against a wall or fence, so he could push himself up. Within 7 days of isolating him, he was able to stand and walk around independently, though he's still a bit wobbly to this day. When we tried to reintroduce him to the flock we had issues with the roos not getting along, so we put him back with the adult flock. However they were not getting vitamins every day. He was fine for 2 weeks then started to show the same symptoms with trouble standing, at which point we popped him back on daily vitamins and he recovered almost immediately (within 1 day). After some integration we've managed to get everyone to get along and now have 1 big flock of 14 chooks. All are now receiving the vitamin supplement with it coming into winter here anyway.
Right now I'm mostly waiting to see what happens when the pullets start laying, as they seem healthy now, while the roos still seem a touch wobbly.
Thanks again for all the advice guys! I am just so glad they seem to be ok (at least for now)