[thehef]

Not sure if you've advanced past a point of no return, so this may or may not help, but a couple of things:

1) OOTP has a somewhat new (not sure when it was first introduced) feature that allows you to Reset League to Regular Season Mode. I haven't really messed with this, but it's described as "... in case you want to manually schedule tie-breaking games using the schedule editor." Your scenario would seem to be exactly why this feature exists.

2) In my games, if I have the potential for any ties on the final day of the regular season, I always complete those games without advancing to the next day. This keeps OOTP from scheduling tiebreaker games (if needed) or postseason games. Normally, this is just so I can manually schedule a best-of-three instead of a one-gamer, but also comes handy in those rare instances of a three-or-more team tie, and I want to specify the tiebreaking procedure, rather than go with what OOTP does (or if I need to schedule one or more makeup games).