Scattering delay networks (SDNs) are artificial reverberators whose parameters are derived from source–receiver positions and room geometry. For cuboid rooms, SDNs yield high-quality reverberation in a numerically very efficient manner.Extensions based on multiple interconnected SDNs have been proposed for modelling coupled volumes that exhibit multi-slope energy decay, but rely on heuristically defined coupling factors and fail to reproduce correct energy decay for large apertures. We propose a new topology for coupled volumes that uses only one SDN per room and introduces a transmitting aperture node to connect scattering nodes across rooms. We redesign the scattering operation using a matrix inspired by Acoustic Radiance Transfer. We further refine source injection and receiver detection weights. The proposed method reproduces energy decay characteristics more accurately than the state-of-the-art coupled-volume SDN, with a median EDC error improvement of 6.8 dB, validated using FDTD simulations.