I think it is difficult to even know what the money is spent on for those spending it when you're trying to break it down to a specific source of income. I know I don't keep money separate, money comes in and money goes out.

When we buy things for my DD1 I don't think to make sure it was 80% from her bio dad and 20% from us as is our determined percentage from centrelink. If we did we would be buying a whole lot less because the amount centrelink determines to be spent on a child is very basic.

I don't spend a lot on myself (or maybe I do, depends who is looking if you know what I mean, I'm sure somebody could build the case that I do if they were trying to) but if I did I would be thinking well, isn't it in the child's best interests for their parents to also be looked after too? A parent who is stressed and frazzled with nothing for themself doesn't seem ideal. I don't know, just try to look at it all contributing to their life, their parent is a part of that.

It is the same as how I can't take an audit of the time DD1 spends with her bio dad to make sure it is spent how I'd deem appropriately, that is his responsibility to determine once she is in his care just as how it is my responsibility to figure out how to spend the money once it is in my care. If you don't trust somebody enough, push for more care percentage so you become the one more responsible for the decisions but if you're trusting them with your kids then it seems it should follow you can trust them with the money for them...
THanks for your reply.
I agree with what you are saying and I wish it were so easy. I wouldn't begrudge paying this money if I knew it were being spent appropriately and that we weren't 'doubling up' on payments. My ex husband pays me around $30 a week to care almost full time for my two children (he has them on the weekends). It is my understanding (morally and legally) that this money is calculated by centrelink to pay for things like school fees, uniforms, dental and medical. I do not ask him to contribute anything more. We then contribute $300 a fortnight to a woman who is living a better lifestyle than we are so that she can care for her children only 50% of the time. We pay child support, half of all extra curricular activity fees and then an extra weekly amount to cover school fees, dental and medical. I don't get it.