Thank you for your answer. I could possibly create a workaround with the featured slider instead of the header image but unfortunately I can only assign the slider to Frontpage, entire site or disable it. In my case, I would want the featured slider to be shown on pages only. But this option is not available either.

You could say I may use the featured slider on the entire site but then again, I can’t show the pictures randomly which is what I do with the header image(s).