Academic research on sustainability issues in supply chain collaboration has recently begun to focus more on a network-oriented view. Both horizontal and vertical relationships are being explored, which has led to recognition of the significance of the active participation of change agents in this process. This paper provides a practical example of how change agents shifted an entire chain (pig farming) towards sustainability over 17 years. The longitudinal study examined the mechanics of how change agents in a chain successfully engage others on sustainability issues. A sensemaking approach was used that focussed on three aspects: communication, action, and building relationships. The findings show that the change agents worked on different levels of supply chain collaboration in response to the evolution of the sustainability initiative. Their focus moved from producers controlling the entire chain to engaging in partnerships with other contributors both inside and outside the chain. They translated the abstract concept of sustainability into language understandable for the potential partners, fostering transparency, joined an eco-label certification program, and later invested in experiments to find solutions to new ideas as they arose through reflection. This stepwise construction of a netchain reveals the evolution of reciprocal interdependence in an informal, personal and trust-based way between organizations which can be applied to sustainability initiatives in other fields.