Sorry, I've been out.
Snico, I have to echo what others have been saying. That middle switch can only be two-way in a limited sense because, having only one wire in and one out, it is, essentially, a one-way switch so what you have there is a genuine miracle. (It could work as a second switch in series with another but I can't see how it could independently switch a light on an off irrespective of the position of the second switch.)
Your posts all indicate one thing that is certain though - that you are not (yet, at least) equipped with the knowledge to do this job safely. Please call in an electrician before somebody gets hurt.
Snico, I have to echo what others have been saying. That middle switch can only be two-way in a limited sense because, having only one wire in and one out, it is, essentially, a one-way switch so what you have there is a genuine miracle. (It could work as a second switch in series with another but I can't see how it could independently switch a light on an off irrespective of the position of the second switch.)
Your posts all indicate one thing that is certain though - that you are not (yet, at least) equipped with the knowledge to do this job safely. Please call in an electrician before somebody gets hurt.