Wrobot can use only one offmeshconnection per path, if path need several offmeshconnections you need to combine them. For your problem, you need to create one offmeshconnection "Rut'Theran to Auberdine", one to "Darnassus Portal Down to Rut'Theran" and one "Darnassus Portal Down to Auberdine" ("A to B", "B to C" and "A to C")).
(if I understood the problem correctly.)