This paper presents the conceptual and methodological foundations of a new doctoral project on Multiple Religious Belonging (MRB) in Flanders. MRB refers to individuals who draw on more than one religious tradition in their spiritual lives, an emerging form of lived religion that fits uneasily within interfaith spaces organised around singular, institutionally recognisable identities. Such settings often privilege clearly bounded traditions, producing subtle forms of exclusion or inequality for hybrid practitioners. Their repertoires may be rendered unintelligible within dominant dialogical frameworks, generating epistemic inequality; their identities may be questioned as incoherent or inauthentic, leading to recognition inequality; and their participation may be constrained by representational norms favouring voices rooted in one stable tradition, resulting in participatory inequality. Individuals with shifting or complex identities also encounter limited interpretive space to articulate their experiences, reinforcing narrative inequality. The project investigates how these inequalities arise and how MRB challenges normative assumptions embedded in interfaith dialogue. Its theoretical framework combines lived religion, religious bricolage, and translanguaging for understanding how individuals navigate multiple religious repertoires. This lens highlights the creative ways hybrid practitioners engage with religious boundaries, so far largely remaining invisible. As the project is in an early phase, the presentation focuses on the research design: a mixed method approach including a large scale survey on the prevalence of MRB in Flanders, qualitative interviews, participant observation in hybrid communities, and a spiritual diary method. The paper invites discussion on how MRB research can illuminate mechanisms of inequality within interfaith encounters and foster more inclusive frameworks that recognise complex and intersectional religious identities.