Adiyen Srinivasa Dasan.

I will try to reply with the limited knowledge I possess. 

Our poorvargal considered “Maranthum puran thozha Maanthargal”very important and seriously. There are many instances to narrate from poorvarkal charithram.

1. Once, during Namperumal Purappadu, it was about to rain and since Namperumal cannot be allowed to be drenched, Namperumal was taken inside Thiruanaikkaval (Shiva) temple. However, Udaiyavar was standing outside only. When asked, the reply was since all Jivatmaas are Bhagavan’s property he can go anywhere but as a Bhakta I cannot come inside. (From one of Shri U.Ve. Velukkudi Krishnan Swami upanyasams).
2. When people asked Koorathazhwan, how do vaishnavas behave with ithara devathas, koorathazhwan replied that the question has to be asked in the reverse manner. ( From one of Shri U.Ve. Velukkudi Krishnan Swami upanyasams).
3. Many stories are narrated in Virodhi parihaaram. One such is When Shri Parasara Bhattar asks Smt Andal (his mother) that mistakenly a devathaantharam sambantham happened and what is the prayashchitham, andal replies that partaking of sripada theertham of a srivaishnavan is the prayashchitham. One other instance where one of the relatives of Dasanambi was walking (perumalai manasikamai anubhavithu kkondu) and msitakenly devathanthara sambantham happened, and when he realised he fell unconcsious.

The above is not meant to dis-respect any devathantharams as they are empowered by Shastras. It is just to impart that as Srivaishnavas, we need not have any sambandham with any devathantharams as we are fully related to Paramporul (Emberumaan) through the Lotus feets of our Purvacharyas.

Vachaka Doshathai kshamikka prarthikkiren.