My hen tolerated the chicks for over 24 hours. All were alive - the chicks were happy but the hen didn't seem to be adopting them. After about 30 hours, I tried to move all to a better brooding area, outside of the nesting box. The hen was very distracted with scratching - she was not attached to the chicks - and really wanted to go back to her nesting box.
I figured her hormones were not set in right, and I am brooding the chicks without her, as originally intended. She was not upset that the chicks disappeared. The chicks still seem pretty happy in the brooder.
I have my hen in the hen brooding area and bought some ceramic eggs. So far, she wants to go back to her old nesting area. I'd rather avoid a broody hen in a communal nesting box (too many broken eggs last time). Hopefully she will either accept the new location or the isolation will break her broodiness.
I guess only time will tell.