Ok I have a broody hen which is in a coop with other hens. I've decieded to let her sit and hatch them but I have a small problem. Everyday the other 3 hens move her out of the nest she is sitting in and lays their eggs in it. She quickly returns when they are done but then I am not sure which eggs are fresh and which she as been sitting on. I've tried to mark them with a pencil but by the next day the pencil mark is gone (I guess because of the moisture?) Can I mark them with a marker or will it kill the embro inside? Also with they still hatch with the others disturbing her everyday or should I just give up since I have nowhere else to put her?