If my divorced spouse remarries and then has her new husband living with her and providing for her (and ostensibly our child if she gains primary custody), could her new additional household income contribute to her gross income and thereby affect (reduce) the amount of my child support payment or does she simply keep receiving the same amount?
No. Household income isn’t used in CS. The court will look to her income only, not the stepfather’s. Although practically speaking stepparents often provide some financial support for their stepchildren, they are under no legal obligation to do so. Therefore, only the parents income will be factored in.