Nirmala is Ammayappa's sister and they all come to Ammayappa's home for Arunachalam's sister's wedding. That gives the opportunity for Vedavalli and Arunachalam to fight first, then fall in love with each other.
Nirmala is Ammayappa's sister, and they all go to Ammayappa's house for Arunachalam's sister's wedding. This leads to a conflict between Vedavalli and Arunachalam, which eventually turns into love.