You want to park on the right-hand edge of the road. Who has priority in this situation?

When you park at the right-hand edge of the road, you are doing a manoeuvre that changes your position in traffic. In German rules, anyone who changes lane, pulls out, turns, parks, or leaves a parking space must do it without endangering or hindering others (the “whoever changes must yield” rule).

So if a blue car is already driving on the road and you want to move over to the right to park, that moving traffic has priority. You must wait until it’s safe, then indicate, slow down smoothly, and pull in without forcing the other driver to brake or swerve.

A useful rule of thumb for similar questions: vehicles that continue straight in the lane generally keep priority; the person who is starting a parking manoeuvre has to fit in and give way. This is also why, if you were leaving a parking space, you would usually have to yield to passing traffic as well.