Color-composite image (as in Fig. 1) of the galaxy group in the northern field of MACS 1149. Shown are the cluster members (red) and the multiple image systems (white). Furthermore, we indicate three line-of-sight galaxies (magenta), with the corresponding redshift values, and two cluster members (red-filled circles) whose effect on the total lens mass model was tested (see Sect. 4.4 for more details).