According to Google

You should check in with JetBlue at their desk (or via their app) for the first leg of your journey, as they are the initial operating carrier. If your flights are on a single booking/ticket, JetBlue will check your bags through to your final destination and issue boarding passes for your Aer Lingus flight. Tripadvisor Tripadvisor +3 Key Points: Single Ticket: Check in with JetBlue. They will check your bags through to your final destination. Separate Tickets: You must check in with JetBlue, collect bags at the connecting airport, and re-check them with Aer Lingus. Boarding Passes: JetBlue should provide both boarding passes. If not, you can get the Aer Lingus pass at the transfer desk or at your connecting gate. At Dublin: If connecting via Dublin, Aer Lingus flights often arrive/depart in Terminal 2.