Observed shear ratio of an elliptical lens L1 at z = 0.4 for sources at a projected separation of 100 arcsec, in the presence of an additional foreground galaxy L2 at z = 0.1 that is located at (x,y). In the left-hand panel we show , the ratio of the average shear along the major and minor axis. The location of L1 is indicated by the blue ellipse in the centre of the image, the location of the sources by the cyan dots. We find that depending on the position of L2, the shear ratio either increases or decreases. The black solid lines indicate the position of L2 where remains constant, the red dot-dashed (green dashed) lines indicate a decrease (increase) of of 0.2, 0.4 and 0.6, respectively. In the right-hand panel, we show , the shear ratio corrected using the cross terms. For large L2-source separations, the induced shear on the lens and the sources is almost constant, and is effectively removed using the cross terms. For small separations, the residual is large as the applied shear from L2 varies strongly along the ring of sources. Note that both L1 and L2 are modeled by an SIS.