The predominant literature examined smart home technologies from an individual perspective. However, it remains less explored how multiple family members interact with smart home devices (e.g., their coordination, synchronization, and task allocation) within social and cultural contexts. This study aims to explore obstacles and opportunities in designing smart home systems involving family-member interactions. We present a multi-case study involving 11 case families using smart home devices, conducting 20 in-depth interviews with their members. Drawing on a distributed cognition perspective, our thematic analysis identified three main obstacles in family interactions: insufficient experiential learning, inefficient synchronization of information, and user-unfriendly collaboration mechanisms. The findings highlight the need for design opportunities, including differentiated learning approaches, improved information flow, and better collaboration mechanisms for smart home systems to enhance user experience and efficiency. This study provides deeper insights into socio-cultural dynamics within smart home systems, contributing to smart home scholarship.