The dead keets are most likely getting stepped on.
If it was me, I would take all of the eggs, candle them and put all the viable eggs in an incubator.
It's up to you. If she tries to take them out of the coop too soon you may lose them. If they are raised by the flock, they will readily merge with the flock.
If you put them in a brooder, later merging with the flock will not go as smoothly. If you are planning on selling them as keets, it...