compare or merge 2 or 3 folders?

 

 

Use Ctrl+M or the menu Document /  Comparison/Merge / New Folder Comparison.

It opens an empty view in which you can use combos to select folders (or a Browse button/menu). See How to Manage a comparison/merge view...

 If you wish to move the base folder in one of the source toward a displayed folder in the tree view, drag and drop it with the mouse on the combo.