Hey. I also did my parents FA application. Sadly, not everyone’s parents are literate or understand financial jargon. I acted as my parents when emailing AO at schools/
My mother does not work while my father does in a low paying job. No one was expected to do anything and potential contribution is around 1k for a family making 25k a year. Those are not exact numbers but you can get the jist. Schools will negotiate packages if you are not able to attend due to costs because they already accepted you and they will be willing to change the price.
I know that the PFS has a section of custodial and non custodial parents and they will assess the situation. If the non custodial parent is not willing to pay, they will not put that against you. You have to state that in the special considerations in the PFS.