Do you have documentation that your ex has not complied with court-ordered support? Your waiver is MUCH stronger when you’ve got a “I petitioned the court on XYZ date to garnish his wages” situation vs. “He owes me money” situation.
I would also get a letter from a clergy person who knows your D (if there is such a person) to attest that she’s had no contact with her dad since XYZ date. I think the colleges are leery of the “Her dad is a bum” scenario vs. “After years of a good faith effort to maintain contact with her father and to have him comply with visitation and financial support per the divorce decree, she has effectively been abandoned by him”.
Just a suggestion. A VERY high percentage of divorce situations involve “s/he doesn’t want to pay his fair share”, which if I read your description with my cynical hat on, is how it reads. Not saying that this is accurate- but it’s certainly one way to read it.