When you quarantine basically you do leave them alone. You will want to have a different set of equipment too. When I quarantine mine they are in a separate room and I try to check on them every other day or so, but I never handle any of my established collection again until I've showered and changed my clothes. I use different feeding tongs for them, and I try to feed on a different day. I also clean their cages last.
It doesn't really matter who you got them from because you don't know what they could have been exposed to during shipping or at a reptile expo.
If you add a new snake while you have one in quarantine you reset the quarantine clock so they all leave quarantine at the same time.
It's not worth it to risk your existing collection.