Sharing a single Dropbox between multiple accounts on one Mac - possible? This seems like it should be easy, but...

My partner and I use a single Dropbox.com account to keep all of our joint projects synced up between our computers - and this has been working great for years. We've now added a MacBook Air to the mix, and we each have accounts on it and can grab it and go when we need to do some remote work.

I've been trying to get the Dropbox synced to the Air - but I want to have it in the "Shared" directory so that we both can access it - it shouldn't matter who is logged in. This doesn't seem to be working.

I can located the Dropbox in the shared directory fine - but when I change the user who is logged in that user has no permissions to sync the Dropbox or access the files.

I can get it to work if I create a separate ~/Dropbox folder for each user, but this ends up with 50GB duplicated twice over if the entire Dropbox syncs - a particularly ridiculous waste of space on an SSD.

Any ideas how to make this sharing work????
You can do this using ACLs, which will avoid permissions problems when new files are created:

sudo chmod -R +a "$USER allow read,write,append,delete,list,search,add_subdirectory,delete_child,file_inherit,directory_inherit" "$DIR"


where $USER is the username of the other user, and $DIR is whatever directory (Dropbox or otherwise) you want the other user to have full permissions in.

We use this to share a single Dropbox folder between four users (2 adults with full access, 2 kids with access to their subdirectory only), and it has been working well for us.  The only limitation is that the user running Dropbox has to be logged in and running Dropbox.  The other users don't have the Dropbox icon and status info in the menu bar.