Wishlist Candidates: Collection back-ref; Searching outlines

Good Morning (at least ‘here’) …
:arrow_right: For me, Collections are not often a gathering of linked extracted text. In the early stages of thought development, it is not unusual that a broad discussion in a source document would apply to more than one of the wheels spinning.
It would be nice to quickly find the collection(s) that uses a particular document.
Going the ‘other’ way is doable, using Project Search for some embedded string and so on. However, when I change a self-sourced document’s wording, I often want to keep its import within the broader perspective of (most of) the collection(s) that use it: I’d like to see which developing ideas (Collections) already include it.
I do expect that such a referential lookup, a reverse Ctrl+Shift+8, might require new processing beyond a mere logic branching to another extant routine. So I might as well add that rather than being only a Binder tool (where it would be of use), I would more likely use such a Collections lookup from the document itself (and appreciate the opportunity to put the resulting list of Collections either in a popup or another editor – you know, pie in the sky).

:arrow_right: Is there a way to FIND a string among the documents shown in an outlined editor?
Without going through “Binder Selection Only” to limit the Project Search appropriately?
It would be nice to Ctrl+f in an outline and merely bump through the hits – from one document to the next.
(I understand that P/Search w/“Binder Selection Only” is not much different. But the current P/Search process still requires the mouse and its hit list still requires that I take another step as needed to identify the document’s (sub) -container.)