Can people added to a discussion see earlier posts?

🔵 VirtualCallboard

Yes. Anyone you add to a discussion can read the whole thread, including posts made before they joined.

To add people to a discussion that's already started, open it, click the people count under its title (for example, "5 people in this discussion"), then click Add or remove people. That link appears for the person who started the discussion and for anyone in the discussion with the Add / Edit / Delete Anyone's Posts/Replies permission.