The original post says they support other family members in another country. That is often the case of immigrants new to the US and the US financial aid system. Schools do not consider that obligation when giving out FA. A family often has to make a choice of supporting the family members or choosing private school (day school, boarding school, college).
Those are personal financial choices. Even the parents having large student loans they need to repay is usually not considered. The main considerations for FA are income and assets. Some schools do consider medical costs the family has to pay or the care of a child with special needs, but usually don’t consider other debt or obligations (the support of other family members).
There are public schools, much cheaper ‘day’ private schools like Regis in NYC, magnet or charter schools that may appeal to the learning style of the student. Lots of choices.