The fashion industry is currently undergoing a radical change towards an overall sustainable paradigm shift. This paper investigates how the fashion collection, as a particular design framework, might be reconfigured as a strategic driver for garment longevity furthering sustainable fashion design. The study builds on a case study of a company offering a subscription service for baby clothing, exploring in detail whether and how the collection is used as a strategic design tool. In the analysis and discussion, feedback from users, manufacturers and the garments themselves plays a crucial role in the development of the collection. To some degree this differs from the development of a linear fashion collection. The paper concludes by suggesting a framework for using the collection as a strategic design tool designing garments for a product service system while adopting a circular economy thinking.