I do not know the grammatical terms for this kind of usage. I can only give an example. I want to describe two boys called Sam and Tom. Of course I can just say
Sam and Tom are nice.
But I want to be a bit clear about their gender. But instead of the a bit verbose
The boy Sam and the boy Tom are nice.
I would like to factor out the boy. Then I am not sure the result would be which one of the following three:
The boy Sam and Tom is nice.
The boy Sam and Tom are nice.
The boys Sam and Tom are nice.
An answer that comes with the grammatical terms for such usage will be highly appreciated.