I can think of a way you can all arrive. The Lincoln has one final push to make before it can leave Jehan, destroying the station and elevator connected to the planet that is acting as a base for the Coalition in the current engagement. You guys, in an attempt to escape the chaos that is Cerol, could have randomly jumped to a nearby location, not exactly at Jehan, but in the star system. Hearing the Lincoln's communications over the battlenet and the signal from Admiral Ardin, your ship moves in to assist the Lincoln.