The fight began after the identity of the buyer came to be known to the family.
The intended buyer was Arjun Aloysius, son-in-law of former Central Bank governor Arjun Mahendran.
Ruwan had tried to sell the channels to Arjun as he had expected a big cut as commission.
Major shareholder Janaka Ramanayake, the managing director of both Max TV and radio, is opposing the sale.
Ruwan, who is married to Chaturi Ramanayake, is the event coordinator at the Presidential Secretariat.