The coupling of square convergent divergent jets in Twin Jet configuration undergoing screech is investigated. Particle Image Velocimetry, high speed Schlieren imaging techniques & Large Eddy Simulations were employed to study qualitative & quantitative aspects of the coupled jet interactions. Comparisons between experimental & computational data were drawn to elucidate the observations made in experimental results & probe the driving cause of the coupling phenomenon. Twin square jets were found to exhibit symmetric flapping motion mirrored about the nozzle symmetry plane. Strong acoustic propagation driven by phase locked shear layer interactions between the jet were observed driving flow propagation in upstream & downstream directions. Tone propagation into the ambient was driven by out of phase flapping of the outer shear layers of the jet. Near field acoustic measurements showed multiple harmonic tones driven by screech & subharmonic tones generated due to coupled shear layer interactions. Flow field results revealed branched turbulence distribution along the inner shear layers as a result of the strong flapping.