Thanks for the lucozade Lyra.
Berrie could you try setting them aside a box each filled with things that they can help themselves to when they are hungry?
Discuss acceptable things like fruit, small amount of dried fruit, crackers, plain biscuits etc and then when they are hungry they just help themselves.
I read about it here on mn a few years ago (can't remember who did it possibly greensleeves). I did try it with dd when she was younger.
Now she will make herself cheese and crackers if she is hungry or have a slice of dry bread.
Poor love has taken herself to bed .
I said that it might be best if she slept with me, and dh had her bed tonight, then if she needs me I don't have to get up.
I made the beds up, swapping pillows etc and went to make dh a cup of tea.
When I went back to her she'd put herself in our bed and was asleep.
Half of her school is off sick and when I spoke to the teacher earlier she said she felt rotten too.