Node-wise editing of Right-angle connectors

I build complex schematic diagrams with right-angle connectors between elements of the drawing.  I wish to maintain the "connected"  property of the connector, but I wish to edit the exact position of the various segments of the line.  

When I edit one of the segments using the node edit tool, the rest of the connector is automatically modified in unpredictable ways.  The "wrap around object" functionality of the right-angle connector doesn't work--or it it is not of use; it operates in ways that I can't understand.  I would like to be able to adjust each of the straight segments of the connector independently of all the others, so the ones I have worked on remain precisely where I put them.

I wrote a simple file to show the problem.  There are three shapes; I need to draw three connectors from the left rectangle to the right circle, keeping them parallel all the way.  To do so, all of the connectors should come out of the shapes at right angles, and I must adjust the intermediate segments for a pleasing look.  It used to be easy in previous versions; if one edited the connector it stopped trying to select a path automatically. Now nothing I do can stop the program from overriding my desires.

Node demo.des