If you get awarded 50-50 custody, do you still have to pay child support? Is child support supposed to be shared equally between mother and father? You pay expenses while the kids are with you, she and her fiance pay expenses when the kids are with them, and then clothes, education, medical etc is shared evenly?Sometime in the 1990s, the feds forced the states to use formulas for child support, and the amounts were increased to make alimony unnecessary. The formulas vary from state to state. In many states, a mom collecting child support under the formula can live better than the dad.
The formulas depend on the time-share and income of the parents, as well as the number of kids and a few other factors. If the custody is 50-50 and the parents have the same income, then there is no child support. If the custody is 50-50 and one parent earns more, then the parent earning more pays to the parent earning less. The formulas don't have anything to do with the actual child-related expenses, and there is no obligation to spend child support money on the kids.
Your questions allude to a really bad aspect of the formulas -- they encourage moms to fight for custody purely as a way of getting more child support money. If the formulas were made more just, a lot of custody fights would just disappear.