Child support changes with a new baby

My hysband has a kid from before. All is well with that. He pays child support and visitation has gone smooth for the most part. She sometimes causes drama, like when we got together, got married, pregnant and any time she breaks up with whoever she's dating.

It's been about 4 years since the custody/support agreement was put into place. In that time my husband seen regular cost of living raises, but that's it. She on the other hand has gotten a significant raises and promotions at her work. So she makes way more now than when they split up.

My husband wants to have the child support recalculated once our baby comes to see if what he gives her can be lowered. I know that will open pandoras box of drama, so if it's not worth it I'd rather just forget it and keep things the way they are.

But given the facts, would he be entitled to lowered payments? Or not.