Can I replace the eggs of a hen that is already sitting on another -infertile on candling- batch for 10-15 days?
What are the chances of successfully incubating them and not abandon them once 20-25 days of total sitting time has passed?
It's possible to have a successful hatch but it's a risk for the hen and the eggs. The hen is getting very limited nutrition so the additional time would be hard on her. If she gives up out of self preservation then you'll loose the eggs. You have to make the decision.