My thoughts- there hasn't been any research to prove the live cycle of the free floating form of the disease, so you go through all the effort of catching and stressing the fish then the difficultys of running a QT and keeping the water good thus not cause more stress to the fish then put them back in to only get another outbreak.
How do you know the disease wasn't already in the tank from live rock or corals added?
Some species of fish fall ill easier than others so it may well have already been there.
Like Marty said, keep them well feed with a variety of foods and you could try soaking it in garlic guard.
I have been treating my Kole tang and Royal grammar for white spot with polyp medic but I can't say if it works as I only got to day 9 yesterday and had to go on holiday, the grammar had got rid of all spots and the Kole tang was looking better, can't say if it was the meds or feeding.
Hope your fish all ok what ever you do.
Also lower light levels