Do schools consider a family's student debt when calculating financial aid?

For colleges that require the non-custodial parent information, you need to include his information in the NPC to have any chance of it being accurate. Also, you need his cooperation on the CSS Noncustodial Profile unless it is waived. If he is non-cooperative, then no financial aid unless the college grants a waiver.

Furthermore, you may guess that his income is only $10k per year, but if it is actually significantly higher, and he is somehow cooperative with the CSS Noncustodial Profile, then you could see an unpleasant surprise when actual (smaller) financial aid offers using his actual higher income show up.

If you want to apply to a fast-track-to-Wall-Street college, try Princeton. It requires the non-custodial parent information in divorce cases, but has an exception in not requiring that if the custodial parent has remarried: https://swebapps.princeton.edu/FinAid/finaid_form.pl and https://admission.princeton.edu/cost-aid/apply-financial-aid/additional-aid-application-requirements .

Most “prestige” colleges generally require non-custodial parent information. Chicago and Vanderbilt are exceptions.