The premise is challenging. I don't know of any other movie employing it. I firmly believe that only a person as contrived as Balachander can imagine such a premise. It is another issue that he handles the premise in his own contrived way that is at-once cliched, repulsive, yet interesting and extracting the very best from all his artistes. You have to have a certain taste to enjoy such movies. Since they are often extremely subjective visualizations of the director's contrived mind, not everyone likes them.
Anyway, I will end this review merely stating the premise: A son with a single parent (father) and a daughter with a single parent (mother). (They are unrelated families.) Each has a certain misunderstanding with his/her parent and leave the house. What happens then is interesting. The father meets the daughter and falls in love; the son meets the mother and falls in love. What is to happen if they marry? Pretty daring for 1975, I would say! Go figure.