EFC confusion; 1 in coll last yr = $35k; now 3 in coll =$20+$20+$20??

My son has been accepted to Misericordia as well, and it is his first choice, we received the financial aid offer yesterday, only offered the presidential scholarship of $15000, $1000 non PA resident grant,$1000 merit and loans. The total cost that I Calculated was $42500. I also have will have 3 in school, no “need” based aid offered. I emailed the admissions rep today to appeal the financial aid offer. She replied stating that there is a process so I hope for more grant aid.