The acoustics of coupled rooms is often more complex than single rooms due to the increase in features such as double-slope decays, direct sound occlusion and anisotropic reverberation. For directional capture, analysis and reproduction of room acoustics, spatial room impulse responses (SRIRs) can be utilised, but measuring SRIRs at multiple positions is time consuming, and thus it may be desirable to interpolate between a sparse set of measurements. This paper presents a perceptually informed interpolation method for higher-order Ambisonic SRIRs that is robust for coupled rooms. It uses minimum-phase magnitude interpolation of the direct sound which is steered to the relative direction of arrival, sector-based early reflection interpolation in the frequency domain, and relative RMS matching for late reverberation. A method for rendering up to six degrees-of-freedom datasets of SRIRs is then presented using a time-varying partitioned convolution audio plugin, which is open-source and has made available for download. Finally, a listening test is conducted to assess the perceptual quality of interpolating between coupled room SRIR measurements with varying inter-measurement distance. The results suggest that for the tested scenario, using the presented interpolation method, a 50 cm inter-measurement distance is perceptually sufficient.