I don't think I could consider either a PB. I've put together some really great 9 hole scores, but it's hard to keep hanging on for the full 18 at the same time. Once you start thinking about score and getting tired, things usually start going down hill for me, so for me to consider it a PB, it would have to be one continuous round in one day.
While it would suck I couldn't consider it a legitimate PB.
I would (and have in the past) had those rounds posted together for handicap purposes but something so special as a PB (especially that much under par) needs to happen together.
It has to be 18 consecutive holes for me to celebrate an 18 hole PB. I've played plenty of good 9's, but I know that, at least for me, putting together an entire 18 hole round can be a grind. That said, if it's a 9 hole PB, I'm going to celebrate that.
I don't believe I would count that for either scenario. What if it was not only a PB but I also broke 80 for the first time with say a 79? Certainly not for scenario #1. But for a next day rain delay I am not sure. Doesn't that count for ones round when the tour gets delayed? If its a course tour record does it not then count? Hmmmm, I don't really know????