http://bbergeron.i2p/posts/2024-11-14_how-to-merge-divergent-git-histories.html
First, here’s a short overview of how one might have gone into this
situation: mkdir monorepo cd monorepo cp ../frontend . ; rm -rf frontend/.git cp ../backend . ; rm -rf backend/.git git init # (edit, add, commit, push, repeat ...) The Solution In this guide, we’ll import a single repository history into another
one, but you can repeat the process as needed for each history you wish
to import.