Please remember that Excelsior is a last payer score that can only be used for tuition. It will pay the balance after all other sources (federal aid, state aid and scholarships are applied).
Should you get merit money from Stony Brook, it will be applied to qualified educational expenses (tuition) first. For example, the cost of tuition is approximately $6700. If you get a $3000 scholarship, you will get $3700 in Excelsior (minus any monies you receive from TAP) to cover the balance of your tuition.
If you get a 6k -7k scholarship from Stony Brook, you will not be eligible for Excelsior because your tuition is covered.