Years ago I had a plug-in (Reflective Objects by in-tools) that could position objects, for example, relative to the spine, so, for example:
1) I create a text box on the left page and set it relative to spine.
2) Pages are added so that it becomes a right-hand page.
3) Object maintains distance from spine, but on right-hand page.
I could swear that ID now had that capability (or some of it) without workarounds... is that the case?
No, not directly. You can anchor a text or graphic frame in another text frame and define the relative psoition of theanchored frame via object styles.
Ah, that's too bad. Thanks.