a) Observed value of f_mm (dotted line) and (solid line) for a lens L1 with an SIE profile and ellipticity (e₁,e₂) = (0.2,0.0), measured using sources at 100 arcsec, as a function of r_out, the projected radius from L1 within which the contributions of L2 are integrated. The black lines show the reduction if L2 is an SIS, the green (red) if L2 is a TIS with a truncation radius of 150 (50) arcsec. The dashed line indicates the shear ratio in the absence of L2. This figure demonstrates that L2 at projected separations >100 arcsec from L1 have a non-negligible influence on the shear ratio. Multiple deflections reduce the observed shear ratio, but using the cross shear we can correct for most of it. b) Observed value of as a function of source radius, for an r_out of 4000 arcsec. The reduction of increases with increasing L1-source separation. c) Difference between the observed value of and the shear ratio in the absence of multiple deflections (f_mm,noMD) as a function of the ellipticity of L1, measured at a L1-source separation of 100 arcsec, for an outer radius of integration of 4000 arcsec. The reduction of the shear ratio increases with decreasing ellipticity.