Hi Silvio,
first a translation into German. It took a while to find a transaltion using translate.google.com and dict.leo.org but finally I managed to understand what you meant (unfortunately there are no proper translations for expression in those dictionaries...)
"Wie werden Gleiswendel im WDP-Diagramm dargestellt?"
Silvio, this you can any way you want. WDP is not a planning program but a control program. Thus the rails drawn in WDP do not have to be exactly drawn like the original. To be extreme you even could draw a helix (helical) as a line! The only thing that's important is the order of the feedback contacts which has to be the same in WDP as in your model railway.
There are some WDP users who draw a helix as a single loop. I enclose a screen shot of a part of my WDP layout where you can see how I painted my helix (which is not finished as you can see).