What's fair to pay for 2 children's dinners?

[curryeater]

My two dcs, nearly 2 and nearly 4, go to a CM full time. She gives them lunch, which we agreed at the beginning, but now she has suggested giving them dinner too because her own kids get hungry when she delays their dinner so mine have gone before they eat. (Mine are gone by 5.30 - we are not making them wait till 8pm or anything)
This would be quite convenient but the horrible truth is that we are so, so financially stretched that I don't want to over-pay for this. I can't say yes without offering to pay, obviously; but on the other hand, we are cutting expenses left, right and centre and employing someone to make meals for my children wasn't high on my list of priorities when we can do it ourselves and be eating by 6 or soon after (which they are fine with).
(Also I don't know what they eat, but let's assume for the sake of argument that it is fine, I can find out)
What do you think I should offer to pay for 2 dcs dinners 5 times a week? I think they have normal appetites for their ages, if that makes a difference, have no allergies and are not fussy eaters.

I don't charge for meals. The cm that I know expense the meal costs. We always eat at 5pm to ensure those who are collected at 5.30 and 6pm have all eaten and are cleaned and organised by the time their parents arrive. I would find it difficult to have children not at the table as feeding 8-10 is tricky enough trying to feed them, engage them socially and help their table manners. Children are easily distracted and if some were not at the table it would be hard to keep the others seated and the cms happy who were left out. I imagine that if your cm is already cooking she would be grateful to have your children at the table. Does she charge you for lunch? If not she probably won't charge you tea. As the others have suggested it is worth asking what she would charge and saying you would think it over. She may very well not charge :)

I dont charge extra for meals. I find it easier to cook for everyone at the same time and it means the parents dont have to do it at 6pm or later when they get home.

One of my children still eats with the mindees but the other eats with us later.