Well, you're not using some sort of version control, no?

Overleaf is probably easier for casual interaction, but for substantial work with savvier collaborators, why not git?

Org-mode publishes to LaTeX, and org-babel does tangle/untangle round-tripping for literate programming. Whether there is any prior art could tangle-untangle a LaTeX file for Overleaf interaction is unknown to me, and sounds like a Rube Goldberg workflow at best.