I think today we're down to 5 chicks surviving from the original 11-strong brood. Mum clearly removed at least 3 dead chicks from the nest this morning. I guess it's the most effective thing to be done. Early this morning there were still 6 left, but it looks very much as if one of those expired over the course of this morning. In some ways it bodes better for the remaining 5 as they'll get more frequent food. But I hope the current rate of attrition doesn't continue - I hope the food they're getting is the right type and sufficient. Makes me wish I'd sorted out the mealworm option, but others on this forum don't seem to have always had success with this, so perhaps it wouldn't have improved anything anyway.
Pics 3, 4 & 5 are the evidence I have for mum removing the dead chicks. All done very quickly without much fuss.