The Publishing main tab preview shows the mixed GN4/VirtualCom content. On the following screen shot, the GN4 articles are on the  positions 1, 3 and 4. The VirtualCom article is on the position 2. The drop zones are visible as dashed red rectangles (right-click and select Toggle drop zones to hide them).

You can drop a GN4 article on a VirtualCom article zone, pushing it in the next available position.