Thanks. Worked for me. I needed to move the merged directory into a sub-folder so after following the above steps I simply used git mv source-dir/ dest/new-source-dir

In case you want to put project-a into a subdirectory, you can use git-filter-repo (filter-branch is discouraged)

New changes to the old repositories can be imported into the monorepo and merged in. For example, in the above example, say repository one had a branch my_branch which continued to be developed after the migration. To pull those changes in:

Let's say that we want to extract a piece of a repository, with the intent on merging just that piece into some other bigger repo.

The transclusion doesn't automatically change along with it. If transclusions were direct embeds of the original content, we'd end up with link rot on a whole new scale. Every document would be a sad compilation of 404's.