Pannvalan ji,
Aram valartha nayagi is in tiruvaiyaru na??? Might be there are two such deities. But, in thriuvaiyaru "Dharma samvarthini", the consort of Iyarappar is there.
Whereas, her query is dharma devathai (I think Yema dharma raja). There are some shrines for dharma devan in Shri vanjiam (near Nannilam), Thirupainjeeli (in Trichy). But, I dont know about the temple in Tirunelveli dt. In Karnataka, dharma devatha worship is very famous. Even there is a dharma devatha temple near Kerala Chavakkad.
Pranams