OK, that makes sense whilst the clutch of eggs remain in the nest but once the cuckoo chick has ejected them there is no reason for the birds to continue nestin

OK, that makes sense whilst the clutch of eggs remain in the nest but once the cuckoo chick has ejected them there is no reason for the birds to continue nesting there. As I said to nullc there has to be some other reason why, say, the Reed Warbler continues to feed a cuckoo chick twice its size with now no viable offspring of its own if it's not oblivious to the fact (see video in that post).