Is there a way to add the hours from laborer's union to operating engineer's union?

My dad worked and was part of the laborer's union for 8 years. He switched jobs to operating engineer and became part of local union 3. He's been working as an operating engineer for 18 years. Is there a way to add the hours from his last union to his current one? He was supposed to retire 2 years ago with the combined hours. Thanks in advance.