I have gone in circles and nobody has been unreasonable YET so this is a backwards AIBU thread 
What is the fairest way for my siblings and I have a secret santa pot which is fair to everyone in our different circumstances? Help me...
Siblings
A - couple, two children
B - single mum, two children
C - couple, two children
D - couple no children
E - couple, one child
5 families
9 adults
7 children
We've agreed on a secret santa type pot so everyone gets one present of equal value. And less 'stuff' for the children.
Everyone agrees to spend more on the children than the adults.
We all typically spend £15-20 on each child and we've done all sorts of deals with adults - some agree not to buy each other to save money whilst others are happy to spend regardless.
It is hurting my brain. Should each family put money in the pot, or each adult?
How do we prevent unfairness to the childless couple? Or the single mum?