I had two hens laying in the same nest before and they both went broody in there on top of each other! One gave up after two weeks and the other was then sitting on about twenty eggs, 15 hatched the others weren't getting enough heat to hatch and some just rolled out of the nest, the only thing i would suggest is either cover the nests with wood during the night and taking it of in the morning after the others have laid or move the broodys and there eggs somewhere which is inaccessible to the other chickens they should sit back down on the eggs no problem after you move them.
