Dear
Mark Stephen Mrotek
Pierre Perol-Schneider
Hans Åberg
Lukas-Fabian Moser
Jacques Menu
Wow, the extremely quick response here is more than anyone could expect. Thank you all for your very nice comments and suggestions. I have to do some homework to get it right. I am confident with your hints that I will succeed and share my solution with you. I know, all that counts is practice.
And thanks to everyone in advance who might also chim in.
When I have more practice, I also hope to contribute solutions and answer questions...)
Have a nice day
Roland
P.S. I believe, I have enough information for now. But as i was asked to send a picture, I am doing this. I am using the Henle edition from 1960 for the Bach Fugue IX BWV 854.
In measure 7 you can see the connecting bar for the middle voice from dis to fis.
Another voice crossing in measure 25 also in the middle voice from B (German H) to Cis.