Requirement traceability ensures that (SW-)products meet their requirements and additionally makes the estimation of the consequences of requirement changes possible. It is especially difficult to establish at the transition from requirements specification to its provision in the design, because design processes represent creative and complex transfers of mostly unique problem constellations into a sustainable solution (so-called Wicked Problems). At first, this article searches for symptoms of the problem in analyzing the process model of ISO 12207, the foundation of SPICE or CMMi. This analysis mainly serves the derivation of a concept for the integrated extension of today's traceability models with the aspect of documented design decisions. In the context of current approaches in Rationale Management, our concept proofs as sustainable solution that supports - heavyweight" prescriptive approaches as well as - lightweight" pragmatic approaches and -moreover -shows interdependencies between both kinds.