Yes, that's exactly what I'm saying. Of course, we do have to take into account that the Kid in this situation never time traveled--unless we consider the Pendant reversing her injury from Lynx as time travel--and thus would not have Time Traveler's Immunity and thus WOULD remember Serge saving her, but only after the event of going back. Once that happened, the timeline where she escaped on her own is discarded to the Darkness Beyond Time and the new timeline is put into place.
The key is whether she has Time Traveler's Immunity or not...if she does, then she will still remember things as they occurred in the previous timeline, but if she doesn't, then she will now remember Serge saving her, though it's possible she might not recognize Serge down the road when she saves him from Karsh, Solt, and Peppor, giving the time that had passed since she was saved.