I married a woman with 3 children. Father was ordered to pay child support but never did. When the little one was 12 1/2yo, we divorced (I had been around for about 10 years).

In order to not pay lawyers, I agreed to the following:

1. $1000 / month until the little one turned 18.
2. I would not claim the expenses on my taxes.
3. She would not claim the income on her taxes.

In other words, I paid over $66K from after tax income(if you gross up the principal and figure the deductions I could have taken it works out to over $100K) and took it up the ass for 5 1/2 years...BUT...

...I have a beautiful daughter who calls me "dad"...and that, my friends, is PRICELESS.