Recently I was in a discussion with a friend who had visited Chidambaram Temple and he was telling me about the legend of Vyaghrapada mentioned in this question but my curiosity was piqued by another statement he said. He mentioned that this lion-legged rishi was married to the sister of Brahmarishi Vasishth and they sired the rishi Upamanyu!
I am aware that Vasishth was one of the Manas Putras of Lord Brahma and all of them were male. As mentioned in the Bhagavata Puran:
Thereafter, Lord Brahma created ten more sons- Marichi, Bhrigu, Kratu, Pulah, Pulatsya, Angira, Atri, Vashishtha, Daksh and Narad. Nine out of them took permission for the creation of their offsprings, but Narad accepted celibacy and resolved to preach Bhagwad bhakti (devotion for God.)
So my question is - Is there any mention of a sister of Brahmarishi Vasishth in any scripture and if so is she mentioned as the wife of Vyaghrapada and mother of Upamanyu?