Most schools use a formula to determine need and don’t welcome negotiation. However, if something in their formula didn’t accurately reflect your situation, you can appeal your award and ask for a review.
I once heard of a family doing this because the school didn’t consider the country club membership a necessity while the family did – the rest of the family used it and they would need to pay the initiation fee again to rejoin. The school did not change its determination, calling that a choice. I mention this rather extreme example because you will, in all likelihood, need to be extremely transparent with the school and you should be prepared for the possibility that some of your necessities may instead be perceived as niceties.
If, of course, your situation has been misread, they will be happy to hear you out and quite possibly provide more FA. I have definitely heard of this happening with some regularity.
You may want to keep in the back of your mind as a guiding thought “If I met the donor who donated my scholarship, would they feel affirmed in the school’s decision?” The FA folks are aware that there are people on both sides of an FA decision-- the student’s family and the donor.