[Context and motivation] Digitalisation in agriculture is a socio-technical process that involves multiple stakeholders with diverse backgrounds and skills, e.g., in farming or technology. Capturing process transformation requires focusing on different dimensions, i.e., system structure, process flow, and actors' goals. Model-driven requirements engineering (MoDRE) techniques can offer the means to elicit and represent this multi-dimensional information. [Question/problem] This paper explores how MoDRE techniques can facilitate information exchange within interdisciplinary teams engaged in agricultural process transformations driven by digitalisation. [Principal ideas/results] We present a preliminary method for socio-technical process modelling consisting of (i) a set of different MoDRE diagrams, namely UML, iStar, and BPMN, and (ii) a procedure to collect the data required for the definition of the diagrams. The method is developed according to design science, and is currently evaluated through an action research study in the context of a living lab (LL, i.e., a network of stakeholders involved in a common socio-technical system) belonging to the agricultural domain. The evaluation with agronomists, practitioners, domain experts, and software engineers shows that the models developed are effective and understandable. Furthermore, the discussion over the completeness of the diagrams led to improved versions of the representations, considering different dimensions of the process transformation. [Contribution] There is little empirical evidence on the use of MoDRE techniques in real-world environments. This study fills this gap by developing a preliminary method for socio-technical process modelling in co-design contexts. The presented evaluation confirms the feasibility of the proposal.