I'm Lucy, and I'd be happy to answer your questions today.
Either parent can request a cost of living adjustment to child support every three years (which usually results in an increase) or can seek a decrease where there has been a material change in circumstances. However, your ex-wife's new husband has no legal obligation to support the children she had with you, so his income cannot be used to decrease you obligation. The judge can only consider to what extent the husband's contributions toward rent may increase your wife's available income.
Similarly, you have no legal obligation to support your new wife's children. It's good of you to do so, but your voluntary choice to make that gift to your wife and her kids cannot be used to reduce your child support obligation to your kids. However, you may be able to use your obligation to your new child to reduce the obligations to your older children, since you are legally obligated to pay for the baby.
Run the calculator to see how much you might be ordered to pay based on your current income and your ex-wife's current income. If it's substantially less than what you're paying now, you may be able to get a change. If it's more than you're paying now, and you request a decrease, you should know that the judge can actually increase your payments.
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