In many application domains, scenarios have been developed that benefit from the idea of ambience; Systems will not necessarily be activated by people anymore, but will react on their own to situations they recognize. It, thereby, must dynamically adapt itself to changes in the technical environment or user context. In addition, such dynamically reconfigurable products must be customized to the individual needs of particular users. Product line engineering can be applied to create these variants efficiently; however, means for handling adaptation capabilities at a generic level are required. This paper introduces the front-end of such a means by describing an approach for analysis and specification of features that vary as a part of reconfigurations at runtime.