Go to the NPCof similar schools, the common rivals for applicants for that school, a couple considered a bit more selective, a couple slightly less and see what their NPCs are. Are there wide variances there?
The direct answer to your question is “yes”. You can discuss the financial aid package and there can be changes made to it. Schools do not like their ED admits to drop the process. It doesn’t look good on them. The ED cycle gets them their sure bets. Do look and see if CDS shows % who do accept ED. Compare CDS info to those peer schools.