Thank you very much indeed, Herbert! From a aesthetical point of view, it would be nicer to have an arrow as thin as the other arrow, and both arrows with identical tips. However, I am already quite happy with your solution!
\ncbar[angle=-90,nodesep=1pt,linewidth=0.1pt]{->}{A}{B}%
Thanks, again, Herbert! Would it be possible to add more nodes? Well, if it is easy and I am not abusing ... otherwise, please, ignore my request.
as much as you like ... you could add some more parameters (up to 9) or using the macro several times
\bArrow{One}{Two}\ blahhh \rnode{A}{uuuuuuuuhhhh}% node B is unchanged
\ncbar[angle=-90,nodesep=1pt,linewidth=0.1pt]{->}{B}{A}Herbert
