About 10 days ago my BO went broody again and was just sitting on her own egg, so I slipped 2 EE eggs under her. All was fine until one week later when she got up to eat and drink and 3-4 more eggs were laid in the nest box while she was off. So these eggs are too far apart in age for her to hatch them all right????
I doubt she will continue to sit on the late eggs once her others hatch out, at least not long enough for the others to make it to 21 days. That is my experience at least. Sorry.