Determining which parent is a contributor when divorced

Hello!

I’m a divorced and remarried parent, and my oldest is applying to colleges for Fall 2026 enrollment.

How does one determine which parent is the contributor in situations where support is provided to more than one child?

My child support payments, which cover two children, are a higher dollar amount that what my ex-wife earns. When determining which parent is the contributor, does one consider the contributions to the household in total, or only to the student?

I pay $2000 a month in child support and my ex-wife makes $1500 a month. Since my child support covers two kids, does this mean I “support” my college-bound son at $1000 (that is, half the total support) or would support to the FAFSA student be $2000 a month?

BTW these are all made up numbers.