directions for linking to other repositories

looking for the best way to go about linking parts from a current repository that my projects live in, to a fork of the FreeCAD-library, so people can pr from there. the most simple way is to manually copy/paste the parts but the former should be possible with submodules or file linking.

Start by comparing the repository-linking approaches named in the issue: manual copying, submodules, and file linking. Define how parts should remain available from the FreeCAD-library fork and how contributors should submit pull requests; done means a selected, documented workflow that maintainers accept.

Written by the indexing model from the issue text.