>Decide on a sufficient amount and everyone contribute equally. What's
so difficult?

>Sheldon

Perhaps you could stress to the "she who thinks one chicken feeds 7"
that her share should be weighed not in number of servings, but by the
pound.
"Suzie... you bring a pound and a half of potato salad... we'll do the
rest".

If that doesn't work remind her that she's not Jesus and can't feed
the multitudes with $6.95 and a KFC coupon". Kev