>More than anything, I just hope they don't swarm.
You should also be concerned about spreadin them so thin they can't keep the brood warm...
>I read all the time that once they have made the decision to swarm, it's really tough to get them to change their mind.
In my experience if they have started queen cells it's impossible...
> I don't know if they had made that decision yet since there were no swarm cells
They they have no committed yet...
> but if they were starting to backfill the broodnest with nectar, what are the chances that that alone, without the swarm cells, indicates they have made the decision to swarm?
They were probably headed that direction, but that's not the same as committing to it.
> This is something I keep wondering about. I have not read about checkerboarding for a while, but I seem to remember something about how there is a certain window for doing it, and that if you miss that window it won't make a difference wether you do it or not.
We are still mixing terms. You've been using "checkerboarding" for opening the brood nest. Now you're using it like you mean "Nectar Managment". In Nectar Managment you would need to do this, in my location, by March.
> Does backfilling the broodnest with nectar = missing the window?
Yes. For Nectar Managment. No for opening the brood nest.
> Perhaps it depends how much is backfilled, and if there is still any space left for eggs.
There is a point where they commit. The only point I have discerned is when they start building cells it's too late.
> Sorry for the rambling....I still am trying to wrap my head around this.
Good luck. Beekeepers have been trying to wrap their heads around swarming for centuries...
http://www.bushfarms.com/beesswarmcontrol.htm
http://www.bushfarms.com/beesexperiment.htm