This study examines how Ukrainians living with Human Immunodeficiency Virus (HIV) and/or using opioids access care after their forcible displacement to Poland following Russia’s invasion of their country. Drawing on 37 qualitative interviews with health care providers, NGO workers, and displaced Ukrainians, we analyze how forced migration reshapes practices and identities within a transnational field of opioid use and HIV care. Using Levitt and Schiller’s framework of transnational social fields, we focus on “ways of being” and “ways of belonging” to understand the everyday practices of accessing care and the identity work required for it. Our findings reveal that displacement often disrupts established treatment and support routines, resulting in a sense of “un-being” when familiar strategies become ineffective or risky. Simultaneously, the analysis illuminates the dynamics of “un-belonging” demonstrating how the institutional identities required to negotiate specialized care intersect with systemic stigma, moral judgment, and the anticipation of sanctions. These processes are shaped by the interaction between Poland’s fragmented, semi-peripheral harm reduction regime and the prior experiences of migrants within Ukraine’s strongly donor-driven care system. We argue that understanding access to care requires attention to the transnational circulation of practices, identities, and stigma. We also highlight the need for more responsive, culturally informed harm reduction services in receiving countries.