Musannaf Ibn Abi Shayba 26:395

Waki’ narrated to us, from Sufyan, regarding a Magian who married his daughter and had two daughters from her. Then, one of them died after the death of the father. He said: To her sister from her father and her mother is the half, and to her sister from her father—who is [also] her mother—is the sixth, to complete the two-thirds. She was veiled by herself.