Looks like you already have it…your first screen shot shows the group is shown in more than one cell as the yellow group is stretched from 7:30 - 9:00 already; but the second screen shot, seems like it is not in more than one cell, the cell looks like it is just split into two since the cell is for just one hour but there are two groups to split into half hour segments.
Thank you for the quick answer , I think I didn’t make myself clear enough.
I meant that in the first screenshot, indeed the group is covering 3 group cells, but it only at the front for the current cell’s group it belongs to (first cell)
In the second and third cell, this group is not in front and the group cell is covering it with its grey background.
I would like this yellow group to cover any group cell of the repeating group, regardless of its parent group.
I tried “bring to front” ths yellow group but it does’nt work.