<p>Healthcare has shifted from paternalistic model of care to patient-centered care where shared decision making is key. The need to share and manage contributions and expertise of different healthcare professionals underlines the relevance of collaborative knowledge management (CKM). However, CKM in healthcare requires one to understand the complexities in integrating multiple aspects of care and the challenges associated with interdisciplinary collaboration and knowledge sharing among healthcare providers. In this study, we use a system modeling approach to understand the complexities in collaborative management of knowledge on advance care planning for multi-morbid patients, within personalized integrated care. To achieve this, focus group discussions (FGD) with 11 participants from Basque Public Health System (Osakidetza) in Spain were involved in identifying the key challenges and developing a systemic thinking model. As a result, three key challenges were identified, i.e., (1) culture, where citizens are not willing to talk about death; (2) healthcare professionals, whose attitude and perspectives need to change; and (3) the current system, that has to change its care model towards a holistic and a shared care model. From the developed causal loop diagrams (CLDs), it is noted that perpetuation of fragmented and paternalistic care is likely to get worse without recognition of the advance care plan (ACP) as a social need and as a crucial part of the clinical practice change.</p>