In most Vishnu temples, the statue of Vishnu is in the center of the shrine, with his wife Lakshmi (and sometimes his wife Bhumidevi) at his side. But I recently went to a famous Vishnu temple near Kumbakonam in Tamil Nadu that's quite different. It's technically called the Narayur Nambi Vishnu temple, but it's more commonly known simply as Nachiyar Koil, or "Lakshmi temple". It has a famous stone Garuda statue which magically gets heavier as it leaves the temple in processions. But more importantly for our purposes, the main shrine has Lakshmi at the center, with Vishnu off to the side!
The story as I understand it goes roughly as follows. The sage Medhavi once prayed that he would have Lakshmi as a daughter. Sure enough, Lakshmi took an incarnation as a baby appearing under a Vanchula tree, whom Medhavi named Vanchulavalli. When Vanchullavalli grew up, Vishnu came in his Venkateshwara form to Medhavi's house, accompanied by Krishna's brother Sankarshana (Balarama), Krishna's son Pradyumna, Krishna's grandson Aniruddha, and Krishna's great-grandson Puroshotthama. (It's not clear to me whether they came in the flesh, or they just appeared there.) Vishnu asked for Vanchulavalli's hand in marriage, but Medhavi was reluctant to part with her, so Vishnu agreed to stay in Medhavi's house. Thus despite being a Vishnu temple, Lakshmi is the one in charge of the household because it's her father's house. Her statue even holds the keys!
My question is, is this story discussed in any Hindu scriptures? The reason I ask is that the sage Medhavi seems to be mentioned in the Bhavishyottara Purana, as quoted in this web page. (I can't verify the quote, because I haven't found the Bhavishyottara Purana online, as discussed in my question here.). The quote discusses a sage named Medhavi son of Chyavana who was engaging in Tapasya, but was distracted by a dancing girl, and then repented for his sin by following the Papamochani Ekadashi fast. Is this the same sage Medhavi? Are there any scriptures that mention him having a daughter?
On a side note, it's said that the reason Sankarshana, Pradyumna, Aniruddha, and Puroshotthama came is that along with the main deity (Vasudeva), they constitute Vishnu's Vyuha forms. But Vishnu only has four Vyuha forms: Vasudeva, Sankarshana, Pradyumna, and Aniruddha. (I discuss Aniruddha in my question here.). So what is the role of Puroshotthama in the Vyuha forms of Vishnu?