Ah perfect SHIFT+CTRL gave me the result I was searching for:)

Thank you for all the support but I have another question for speeding up the workflow.
In other programs it is possible to select edges only on the surface. (for example like in the screenshot, I want to select those circles+brakets with CTRL/SHIFT left-cick -> but I also select then all edges in the background with the dotted lines. Is there a function to temporarily deactivate the dotted lines in the background behind a surface (so I can select only the edges in the "foreground"?

I tried to show it here in those screenshots:
https://ibb.co/LJR6ng9