Abstract : Concern-Oriented Reuse (CORE) proposes a new way of structuring model-driven software development, where models of the system are modularized by domains of abstraction within units of reuse called concerns. Within a CORE concern, models are further decomposed and modularized by features. This paper extends CORE with a technique that enables developers of high-level concerns to reuse lower-level concerns without unnecessarily committing to a specific feature selection. The developer can select the functionality that is minimally needed to continue development, and reexpose relevant alternative lower-level features of the reused concern in the reusing concern's interface. This effectively delays decision making about alternative functionality until the higher-level reuse context, where more detailed requirements are known and further decisions can be made. The paper describes the algorithms for composing the variation (i.e., feature and impact models), customization, and usage interfaces of a concern, as well as the concern's realization models and finally an entire concern hierarchy, as is necessary to support delayed decision making in CORE. The approach is evaluated on a crisis management case study.