How can I create a new group for items in the Sidebar in Finder?

Solution 1:

No. You can rearrange the order of the three you mentioned though - just click and drag to move them.

A possible workaround would be to create a new folder, say "Cloud files", and put it in the sidebar. You could then place aliases of your other folders into that one. This would help trim down the folders in your Favorites section, as well as keep the same quick access to them.

Solution 2:

I use a folder named ------------ as a divider. If you need more dividers you could create a new folder inside the first one and so on, be creative!

Solution 3:

I really can't understand why apple can't implement this, since many finder app alternative have this feature! I don't think it is so difficoult! If it can be of any help to you, I use ForkLift, and it has such feature out of the box