Maybe Tess names her baby Alex in memory of... well, Alex, who ACTUALLY is Danielle's son, who was transported to Roswell through a time/space vortex located in the center of the island, which not only wiped his memory, but gave him FAKE memories to fill the spaces. Now Tess/Claire is pregnant, and she starts to have flashbacks to her former life, and she KNOWS who Alex is. The island is actually an alien sanctuary that was used years ago but which has been abandoned for decades, but they still have cameras, and in her time on Antar, she was filled in on who Alex was and where he'd come from. So she knows who he is, and she knows about Danielle, and Danielle -- crazy savant that she is -- somehow knows that T'Laire knows, and WAMMO! Instant kidnapping plot. So Charlie has to rescue her.
And T'Laire, meanwhile, realizes that with a little bit of tinkering to preserve their memories, the vortex in the center of the island is their ticket OFF the island.