Background: Due to demographic changes and a strained public sector operating in many countries globally, informal care is increasing. Currently, at least 1.3 million adults in Sweden regularly provide help, support and/or care to a family member/significant other. With no sign of an imminent decrease in their caring activities, it is important that informal carers are considered as a key stakeholder group within research that affects them, e.g., the co-design of carer and/or dyadic support interventions.