The notion of composition in the context of combinatorial test design naturally arises in situations where the output of one module is used as an input to another module. Composability of tests plans has several important benefits as it facilitates both test and model reuse in such sequential scenarios. In this paper we describe a method for an automatic construction of composable tests plans, one by-product of which is a test plan for the SUT, obtained by their composition. The proposed method is implemented using binary decision diagrams (BDDs), which allows for an efficient and scalable composition-oriented CTD for real-life testing problems. We evaluate the method on a case study of a composition of two Unix Shell operations.