you can appeal but you probably won’t get any additional monies. BU has covered your tuition and fees, which are Qualified Educational Expenses. It is highly unlikely that they are going to cover room, board, travel and misc. cost (which is the 20k). These are not QEEs. Even if they were to cover them, it would be taxable income to your daughter.
The school did not give you any additional monies because based on your financials you do not have a financial need.
Your D can take a $5.5k un sub loan. If she works a summer job, perhaps she can earn 3k, leaving you with 12k to pay.
What is the fine print of her scholarship? Is there a minimum GPA required to keep it?
Your supporting your family outside of the US is not a basis for an appeal. You are the first in line when it comes to paying for your child to attend college. Schools are not going to subsidize your taking care of family members outside of the US.
IF you take a job that cuts your pay dramatically, BU is a school that does not meet 100% demonstrated need. With prior prior, the your child will be a junior or senior before the new income effects your EFC. Unless you take a pay cut that makes your child eligible for Pell, even then, because your D already has her tuition and fees covered, BU most likely will not give you additional monies.
BU is not going to care that your D received a full ride at much lower ranked school so they will not be moved by this offer. Your child is looking to major in studio art; unfortunately not a lucrative major and it may be difficult for her to help you repay any debt.
Your child will not be the first or only child to give up the “dream school” because of money.
If money is the real issue, then you need to sit down with your D and let her know, that while BU is her dream, it is not a financially feasible option for your family and she has to take the affordable option.