The JetBlue page I found for co-located cities indicated that EWR and ISP were not in the same group. Not sure if the page was this one (https://www.jetblue.com/help/rebooki...ncelled-flight), but the information is the same. ISP is in the Long Island group, EWR in the New York group. I assumed that meant they were not "co-located". And in any case, there were no seats left on the one to ISP, and I didn't want to fly standby. I checked and there didn't seem to be any indication of what it meant if you go to choose a seat and they are all X'd out.