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.