Do you mean that the spousal support continues after someone have been remarried? That doesnt seem fair. But it should not change the childsupport because why should the new spouse need to support someone else kids.
No, I actually mean child support. Keeping in mind that child support is basically an equalization payment so that the children can maintain a good standard of living at both houses there is a bunch of math in the Oregon child support calculator for what they call "self-support." But this math (arguably) breaks down if all of the costs of living are subsidized for one of the spouses because of remarriage (or cohabitation).
I'll just make up an example where my ex-wife moves in with Elon Musk and although on paper she makes $0* he gives her a joint CC and she buys whatever she wants with it and doesn't pay any rent. Although Mr Musk would have no obligation to support my
children he has already (in my made up example) decided to support the mother. So suddenly the amount that I'm paying the mother isn't really just or reasonable for the benefit of the children. I could go to court and ask a judge to please fix that for the benefit of my children, and the judge would probably agree. But in the mean time Musk could hire an army of lawyers for the mom and they could go through all my bank statements and tax returns and depose me and ask me a bunch of questions about them just to fuck with me.
The other time that the Oregon child support calculator stops making sense is when one parent (or child) has a bunch of assets, because all the math is based on income. In Oregon parents need to pay child support though 21 years of age if the child goes to college, but does that makes sense if they have a pile of money that they inherited from their grandparent? I don't actually know of any cases like that that have been litigated, but I haven't looked very hard.
Also, because the calculator is based on income you are discouraged from ever realizing any gains, even if you were going to take those gains and put them into your child's Roth IRA.
This post isn't legal advice, it's just life advice to never get married and not have have kids with someone unless you really really trust them. I'm actually on very good terms with my ex-wife and we've never spent a dime on attorneys because we are both reasonable (enough) people.
* - most likely imputed up to minimum wage