Additive Manufacturing (AM) processes based on Laser Beam Powder Bed Fusion (LB-PBF) are governed by highly localized thermo-mechanical phenomena evolving over domains that grow in time. These processes involve steep thermal gradients and repeated thermal cycling, which strongly influence residual stress development and part distortion. The introduction of multi-laser systems represents a significant technological advance, enabling increased productivity and scalability, while simultaneously introducing additional numerical challenges related to the interaction and synchronization of multiple heat sources. This contribution presents a finite element–based numerical framework for the simulation of multi-laser LB-PBF processes. The proposed approach builds upon established mono-laser formulations and extends them by incorporating a set of machine- and process-driven constraints specific to multi-laser operation, without introducing additional physical assumptions. The formulation accounts for layer-by-layer domain evolution, finite element activation driven by laser trajectories, and adaptive mesh refinement focused on the Heat-Affected Zone (HAZ), following strategies commonly adopted in thermo-mechanical AM simulations. In addition, synchronization constraints between laser sources are introduced to ensure physically consistent activation and to prevent laser exposure in regions where no material is present. The main contribution of this work lies in the formulation and numerical implementation of a scalable and flexible modeling strategy suitable for industrial multi-laser LB-PBF systems. Numerical results and detailed conclusions, including a quantitative assessment of multi-laser effects on thermal and thermo- mechanical responses will be presented.