The future 5G and beyond networks need to efficiently integrate the best of all available and under development technologies. In line with this premise, multicast/broadcast technologies bring essential capabilities to boost the potential of future broadband networks. The novel under development multicast broadcast system (5G-MBS) is expected to provide an effective mixed unicast/multicast/broadcast mode embracing the radio bearers single-cell point-to-multipoint (SC-PTM) and multicast/broadcast single frequency networks (MBSFN). This work proposes a dynamic multicast access technique selection algorithm based on subgrouping with orthogonal multiplexing (OM)/non-orthogonal multiplexing (NOM) in SC-PTM 5G networks. The proposal shows the advantages of dynamically selecting among a conventional multicast scheme, a subgrouping approach based on OM, or a subgrouping approach based on NOM, in terms of efficiency of the resource allocation. The dynamic selection is determined by the specific multicast multimedia service constraints and the reception conditions of the users. The effectiveness of the proposal is validated through numerical simulation results. As validation criteria, we consider the system aggregated data rate (ADR), proportional fairness (PF), and the minimum dissatisfaction index (MDI) by considering multiple multimedia service constraints, system resources, number of users, and users' distributions.