Went through this process with my school and was continually denied. Had letters from relatives, a psychologist, and a school counselor and was not declared as a dependent on my dad's taxes throughout undergrad. I didn't live with or speak to my father for the entirety of undergrad and beyond...still didn't make a difference.

Grandparent is talking about a legal process, not letters from random folks.

There’s nothing about getting emancipated that legally obligates schools to care.

Federally, it helps and a lot of financial aid comes from the federal government.