FMOD Studio is designed to match a single project to a single game, so ultimately all people involved with authoring audio behavior with FMOD Studio will need to all be working on the same FMOD Studio project. Consolidating events and mixer routing from multiple projects to a single project is a fairly simple matter of opening multiple projects and copy/pasting across what you need.
As for handling multiple people all making changes to the same project at once, I’d recommend that you look into using source control to track and manage changes to your project - FMOD Studio comes with integrations for Perforce, SVN, and Team Foundation Server. Using a source control integration, you’ll be able to handle saving changes from multiple people and resolve any conflicts that arise from those changes.