Infalling streamline model for the redshifted southern arc structure (outlined in the green polygon), with the same disk orientation but opposite rotation geometry used for Fig. B.2. Top: Streamline model, plotted in green, on top of the moment-1 map of CO, showing the model curvature well matches spatial structure of the southern redshifted arc with the envelope rotation counter-rotating with respect to the disk. Bottom: Velocity components of CO taken from inside the green polygon plotted as a function of projected distance from the central young stellar object, with varying levels of kernel density estimation of the velocity plotted as filled contours and contours calculated as in Fig. B.1. Here, the streamline model also consistently under-predicts the velocity of the arc structure by ~3 km s⁻¹, even thoughthe spatial structure is well matched by the model.