A case-based reasoning (CBR) system makes use of past experience to solve new problems. We introduce a new technique in CBR for facilitating faster knowledge acquisition and solving problems whose domain knowledge is incomplete or hard to understand. We then apply our method as a knowledge-based software engineering (KBSE) tool for reusing software. In our approach, we use multiple cases in a hierarchical representation to represent the design of a software artifact from the system (abstract) level to the code (concrete) level. We propose a feature hierarchy and a case relationship hierarchy and a mapping of features to cases and discuss about the usage and the construction of these mechanisms in our approach.