Not least due to the widespread use of meta modeling concepts, model transformation techniques have reached a certain level of maturity (Czarnecki and Helsen, 2006). Nevertheless, defining transformations in some application areas in our case business process modeling is still a challenge because current transformation languages provide general solutions but do not support issues specific to a distinct area. We aim at providing generic solutions for model transformation problems distinct to the area of horizontal business process model transformations. As a first step in this endeavor, this work reports on the most pressing problems encountered at defining business process model transformations.