Thanks for the great info. So this egg could have come from eitherthe EE or the EE/RIR? I imagine the Maran and the Maran/EE would lay darker eggs. Is that correct?
Yes it could have been ether hen. Are you watching the hens for the signs for which hen is laying?
First signs are the hens start "talking" making quite a bit of long low aaarrrrrr sounds all the time. About a month before laying.
Squatting. They start squatting when you walk up to them or move quickly while standing by them, sometimes they also thump there feet in a little dance while they squat. Squatting starts a couple weeks before laying.
Then a few days before laying they start checking out the nest boxes. Or anything that looks like a good laying spot.
If you have a rooster they will start paying attention to the hen and even start breeding her. If so the layers fluffy butt will start looking a little ragged.
On a day a hen lays an egg you can sometimes see the hens fluffy rear slowly pulsing as the egg moves in position to be laid. It s very slow and can take over an hour from start to egg.
Then if you are lucky the hen will sing the egg song while she lays. Mine don't sing.