From what I have read, it seems that modern historians agree that Lain Calvo and his father-in-law Nuño Rasura Núñez are legendary figures who were invented by 13th-century historians to create a historical legitimacy for the kingdom of Castille. See La nación inventada Una historia diferente de Castilla by Arsenio and Ignacio Escolar. https://fundacion-rama.com/wp-content/uploads/2022/08/1787.-La-naci...
Does anyone have sources for the parent, Gomesindo de Castrogériz, conde currently attached to Lain Calvo? What about the 4 children currently listed?