[Koha] Question about GPLv3 and AGPLv3

[Bob Ewart]

I have installed Koha in a local library.  Our installation is only
available on our local area network, not exposed to the internet.  Early
on we had a request to be able to print our library cards and spine
labels in a format that was not possible by Koha.  So I made some minor
changes to the label and patron card routines  to produce what we
needed.  I'm perfectly willing to share the code I modified, but I don't
think I know how to  re-package it as a source tar-ball.

If we go to GPLv3 or AGPLv3, would I have to make available the whole
source package?

I know that a number of libraries have modified the CSS and the front
page.  Would they have to make the whole source available?

-- 
Bob