Reuse \header definitions: Is it possible?

[Ariel David Moya Sequeira]

Good evening!

I'm currently typesetting a string quartet. So far, I have all separate parts
already programmed, but I want to put all of them in a single PDF file. I was
thinking about using a single \header definition for all the separate parts, so
the same title, subtitle, composer and arranger are shown in each part.

The layout is organized in "bookparts" (one for each instrument) and notes are
defined in variables in separate files.

Is there a way to reuse a \header definition? Do I have no choice rather than
copy/paste it?

Thanks for your help in advance!