Node-wise editing of right-angle connector

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.