I recommend saving your document as a pdf and sharing that. You could save your current Word file with Zotero codes intact as manuscript-working-123.doc and save another copy as manuscript-2proof.doc; strip the Zotero codes from the 2proof version and share it (keeping the current working document intact). Your proofreaders can add electronic or ink to paper comments on the pdf and you can make your own decisions about what of their suggestions to keep.

I demand that my students send me a pdf version of their "final" report 3 weeks before it is "due". I use a tool to add comments and return the document with my corrections. The students then return the revised paper to me usually for an A. I cannot damage their original document. They learn from their errors. All is good.