Edit existing NVT source code / how/where to submit/commit changes

Thanks for the development guide.

Is there a guide somewhere for where to edit existing NVT source code, and how/where to submit/commit changes? I haven’t been able to find information on how or where the community feed plugin repository is actually curated.

Also, is there an accepted way to maintain a local branch for specific plugins that we’d like to tweak for our own use, or is that something we need to create a bespoke solution for?