Is it permissible to complete a compensatory fast after a husband has intercourse while he had forgotten it was dawn? And does this entail expiation?

A woman is not permitted to agree to her husband's request for intimacy while she is observing a make-up fast (qada'). She must remind him of that. Invalidating a make-up fast is forbidden, based on the Almighty's saying: "And do not invalidate your deeds." She must repent and make up for that day, and there is no expiation (kaffara) upon her, because it is only obligatory for breaking the fast in Ramadan.