The Sri Vaishnava sect has two sub-sects, Thenkalai and Vadakalai. Vadakalais follow the teachings of Vedanta Desikan, whereas Thenkalais follow the teachings of Pillai Lokacharya. My question is about Pillai Lokacharya. He was a 13th century Sri Vaishnava Acharya instrumental in saving the Sri Rangam temple from Muslim invasion. In any case, here is what this webpage says about Pillai Lokacharya's father Vadakku Thiruveedhi Pillai:
Sri Vadakku Thiruveedhi Pillai comes in the lineage of the Srivatsa Gotram Mudumbai Nambi (sister’s husband of Swami Ramanujar), one of the 74 Simhasanadhipatis instituted by Sri Ramanuja himself.
My question is, is it true that Pillai Lokacharya's ancestor Mudumbai Nambi was Ramanujacharya's sister's husband?
This Tamil document also says that Mudumbai Nambi was Ramanujacharya's sister's son, and it further says that Mudumbai Nambi had a son named Ramanuja Nambi, and then it traces the family tree from Ramanuja Nambi all the way down to Pillai Lokacharya. My understanding is that Ramanujacharya had two sisters, one sister had a son named Nadadur Alwan, and one sister had a son named Mudhaliandan (who is my ancestor). Nadadur Alwar belonged to Sri Vatsa Gotra, whereas Mudhaliandan belonged to Vadhula Gotra.
Now Mudumbai Nambi and Pillai Lokacharya belonged to Sri Vatsa Gotra. So does that mean that Mudumbai Nambi was the father of Nadadur Alwar? (They seem to have completely different descendants.) Or did Ramanujacharya have a third sister? Also, this is the first time I'm hearing of a nephew of Ramanujacharya named Ramanuja Nambi; I thought Nadadur Alwan and Mudhaliandan were the only ones. Does anyone know if any Sri Vaishnava works discuss Ramanuja Nambi? And does anyone know the relationship between Mudumbai Nambi and Mudumbai Ammal, another shishya of Ramanujacharya?