Compact groups in common in the HMCGs and SOHNCGs samples. The HMCG galaxy members are represented as black squares, while the SOHNCG members are cyan triangles. The inner circle shows the minimum circle that encloses all the group members (Θ_G), while the outer circle represents the disc of isolation (3Θ_G). Each group centre is represented by a dot. Left panel: example of an embedded CG. The SOHNCG (Group ID = 600) lies inside the HMCG (Group ID = 53), while there are no galaxies within the disc of isolation of the SOHNCG. Right panel: example of a non-isolated subgroup (SOHNCG ID = 1115) that lies inside an HMCG (Group ID = 137).