There is a story in which Elizabeth has a twin, James i think. Mrs B dies, and E is sent to be adopted by a distant childless couple related to Mr. b while he raises Jane and James. Illness strikes Meryton, james dies at around age 5, but mr. B somehow retrieves E immediately and begins raising her as James. Meanwhile, everyone thinks E is still being raised by the other family in far away Scotland. By his teens, he seen as a small and youngish looking for his age, but that childhood illness is cited. Because of his smallness, and supposed ongoing weakness for years after the illness, he was never sent to school or university, but educated by mr. B. As his age peers do go away, risks created by hanging out with them are reduced. Bennet cultivates a general unsocial reputation for the family. No one in meryton has any reason to doubt, so they dont. New comers are rare in Meryton, and easily avoided by children, or even teenagers. The plan is that once the entail is broken, James will go on a a trip and unfortunately die, while E returns home. Eventual HEA for ODC.
I think this is on Ao3, and there is an alternate versions in which james is indeed james, not E pretending. Or perhaps she just refuses to let J die and live as E. It's ambiguous. There is still a detailed HEA for ODC. *ahem*
