Seer Karuneegar is a subcaste or part of Karuneegar Caste. There are no further divisions of this subcaste. caste belongs to both Brahmin and Kshatriya Varna (Hinduism)
The people who belong to the Seer Karuneegar community are devotees of Ramalinga Swamigal, a famous Saint who lived in Vadalur and preached against eating meat. He wrote the Thiru-Arut-pa, which preaches the worship of a divine power in the form of a flame and also teaches self discipline for human beings.
Kayastha is the mother caste of all Karuneegars. Kayastha's are brahmins who practiced kshatriya by occupation due to compulsion to fight against enemy forces. Karuneegar Sangams has articles which confirm Karuneegar caste's lineage in Kayastha.
They are said (in the Vedas and Puranas) to have a dual-caste status i.e. Brahmin and Kshatriya. Kayasthas are widely spread across India and are a sub-sect of Brahmins whose ancient profession was writing.
ka_yastha, ka_yata a man belonging to the writer-caste; a tribe of bra_hman.as whose employment is writing
Vyoma Samhita quoted in Shabda-Kalpadrum says:
The Kayasthas have sprung from the kaya or body of Lord Brahma. They are classified as Brahmans.
Karuneegars, basically, shun "meat eating, alcohol " etc. They practise upanayanam, the ceremony for wearing Upaveetham/poonool. Their tradition and wedding methods are more shaivite and similar to the Brahacharanam community.