Document collaboration and co-authoring – Microsoft Support

When you open a shared document in a desktop or mobile app, it doesn’t matter if you’re connected or not, you can keep working. If there are others editing the same document, they won’t be able to see your changes while you’re offline. When you go back online, you’ll be notified of any changes that are available, and others will see that you have changes.

When you’re working in Word, the paragraph you’re working in is locked so that no one can overwrite what you’re working on. When you go offline with Word, it is possible to work on the same paragraph as someone else in your group. When you save your changes, you’ll get a pop-up message saying there is a conflict. You can then click through to where you’ll be able to sort it all out.

If you’re working on a file that’s in a sync folder (such as OneDrive or OneDrive for work or school), it syncs when you come back online, regardless of whether the app (Word, PowerPoint) is running. When you reconnect, your file automatically syncs. If there are conflicts, you’ll get an alert. For more info, see Sync files with OneDrive in Windows.