The eight double-double, Z-/X-shaped multi-component objects at 3 GHz. Top panels: five sources described in Appendix D.1.3 with double-double, Z-/X-shaped radio structure and VLBA observations. Each set of images gives the 1.4 GHz VLA (left), the 3 GHz VLA (middle) and the 1.4 GHz VLBA (right). Left and middle panels: similar to the ones in Fig. 1, while the right panels show the VLBA stamp corresponding to the nucleus; the corresponding radio contours start at 3σ increasing logarithmically, and the beam is 16.2 × 7.3 mas². The VLBA stamps of these objects do not show signs for double core system that could verify the existence of a binary SMBH in the centre of these objects, and which would give rise to a double-double radio structure. The three sources at the bottom lack VLBA identification. The radio/infrared overlays for all objects are described in Fig. D.7.