When points of different layers have the same coordinates, the only way to see them is to hide the top layer. Which is not practical.
Would it not be possible to provide in the menu: STYLE the possibility of working on the inclination of symbols? For the same point present in several layers, one could incline the symbols according to different angles allowing the superposition.
The tips given to users to change the symbol sizes do not seem to fit the uses of our community.