LOL, I was going to reply via work or Facebook but didn't see you.
You know me even at work and "Just do it!" I'd just start draining to the point of still being safe and then refill. If CYA went too low it's cheap to add it on purpose, and you still have pucks that could add more only if on purpose. If you come up a little short on the reduction then you are at least close and can then decide if you run with the still high, but closer, CYA knowing you may have to drain if needing a SLAM, a second but smaller drain, or if no new CYA getting added let mother nature help bring it down. LOL, well, that is probably a little too vague to help you with your parents though. "Sorry Mom, we're just going to do it and sort out the rest later".
You know me even at work and "Just do it!" I'd just start draining to the point of still being safe and then refill. If CYA went too low it's cheap to add it on purpose, and you still have pucks that could add more only if on purpose. If you come up a little short on the reduction then you are at least close and can then decide if you run with the still high, but closer, CYA knowing you may have to drain if needing a SLAM, a second but smaller drain, or if no new CYA getting added let mother nature help bring it down. LOL, well, that is probably a little too vague to help you with your parents though. "Sorry Mom, we're just going to do it and sort out the rest later".