broody chickens

That is unfortunately what happens, they all follow suit.  It is best to try and stop them being broody as soon as they start.  If none are laying I would lock them out of the coop on a morning until bed time.  As long as they have shelter and a safe place during the day.  Try giving them a cabbage hung up for them to peck at so they have a distraction.  Even scattering a small amount of layers pellets for them to scramble for should keep them occupied.  Make sure the pellets are all eaten as they will go off if they get damp and form mould really quickly.

Try it for a few days and then leave the coop unlocked to see if it has worked.  If not continue locking them out.

Watch out for them finding a new nest site outside under a bush or somewhere hidden though.