(...) It is my understanding of the GPL that no such re-submission is required. As long as you agree to the GPL terms and give appropriate credit to the original author, you can publish your mods as a separate work (or upgrade) under the GPL. (...) (20 years ago, 5-Jun-04, to lugnet.cad.dev.org.ldraw)
(...) You are corrrect. Re-submission is not required. Library changes only need to be published. [snip] (...) Agreed. It is bunch of work for just about everybody involved. However, the result is typically better than if you go off on your own. (...) (20 years ago, 6-Jun-04, to lugnet.cad.dev.org.ldraw)
