Overlapping illumination in multi-LED visible light communication (VLC) networks introduces cross-LED coupling that reshapes the received-signal composition and may trigger error propagation in successive interference cancellation (SIC) for layered ADO-OFDM NOMA. This work employs an overlap factor 𝛽 ∈[0,1] to quantify the severity of overlap-induced cross-LED coupling and develops a 𝛽-aware resource-allocation framework for a dual-LED indoor downlink. The proposed design integrates channel-aware MCGAD user grouping with three-level coefficient adaptation, including the inter-LED power split 𝜂, the inter-layer ACO/DCO split 𝜌, and the intra-layer two-user NOMA coefficients 𝛼. Monte Carlo evaluations over 𝛽 ∈{0,0.2,0.5} show that stronger coupling drives the system into an interference-limited regime with a pronounced high-SNR BER floor for strong users after SIC; the proposed 𝛽-aware design consistently reduces this floor relative to a 𝛽-blind fixed-coefficient baseline. Meanwhile, the spectral-efficiency curves remain close to the baseline, with only a minor gap at moderate-to-high SNR, and the Shannon-rate energy-efficiency trends remain comparable across coupling scenarios. The grouping-and-allocation procedure is dominated by sorting and deterministic pairing, exhibiting 𝒪⁡(𝑈⁢log⁡𝑈) complexity and avoiding the combinatorial growth of exhaustive grouping.