Sarfraz Khan, 35, was stabbed to death and three men were seriously hurt when a row over a mop and bucket at the family ice cream business escalated.
Mohammed Nasar, 32, and Tariq Mahmood, 26, of Cecil Avenue, Great Horton, were found guilty at Bradford Crown Court.
Amjid Ali, 39, and Amir Ali, 19, also of Cecil Avenue, were cleared of murder but found guilty of manslaughter.
Nasar was also convicted on three charges of causing grievous bodily harm (GBH) with intent, and Mahmood was found guilty of causing grievous bodily harm with intent.
Ali and Ali were convicted of unlawful wounding.
A fifth defendant, 33-year-old Sajid Hussain, also of Cecil Avenue, was found not guilty of charges of murder, manslaughter, inflicting GBH with intent and unlawful wounding.
During the trial, the court heard there had been bad blood between two sides of the extended family and the row relating to Rossi's Ices was "the straw that broke the camel's back".
Two men have been convicted of murdering a father-of-four in Bradford when a family feud turned violent.