Robertson said Sitiveni, who was known as Steven around the packhouse, was like a father to many in the workplace.
"You wouldn't find a nicer couple of blokes around. They would drop everything to help anyone."
He said both men were rugby fans and would take any opportunity to watch their favourite sport.
"Koli was right into rugby. They loved rugby and they absolutely loved the All Blacks. Any chance they got they would watch rugby."
He said the pair were highly skilled workers able to turn their hand to any job on the floor. After just one season Koli had been promoted to a supervisor role.
Robertson said he and his fiancee Alex Harris had been looking forward to catching up with the father and son in coming weeks.
They had formed a firm friendship when they worked alongside them the previous season. His fiancee had helped Koli with his English and he and his father shared a special supportive bond in the packhouse environment.
"Koli became like a big brother to her and Steven like a father."
He said news of the death had been heartbreaking but the Vaipulus would be held in great affection by the couple and never be forgotten.
The crash also took a toll on a second extended family, who lost two brothers-in-law.
Samuela Taukatelata was married to the sister of Sione Teulaka, according to cousin Manoa Sisfa Tangi.
