I'm assuming you are placing one ID file into another as an image, right?
A placed ID file is no different than, say, a placed PDF or a bitmap. You can access its image properties (size, position, filename) but its contents are on disk and ID only shows a preview. If you want to edit something in a placed ID file, you can do so with scripting, but the very first thing it has to do is open the actual file. At that point, you can edit it to your heart's content and save. The other document will notice the link changed, and will request an update of the (still external!) file.
That makes sense.
The 'linked' file is a template, really, and is meant to be immutable. IE: I change it's contents only in the context of my current operation, and then revert. That's how it's done right now. I open a document, make substitutions, render, and then close the original document WITHOUT saving changes.
So, what I must do, apparently, is open the linked document, make changes, "save a copy", and whilst opening it's containing document, I re-link to the copy, make subsequent substitutions, render, and finally revert. I could then dump the "copy" of my link to the bitbucket.
Does this sound logical?
Does this sound logical?
Eh, sorry, no. You are still over-estimating the information ID stores inside your 'current' document for a link. A link to an image on disk is just that; the file still has to be there, or InDesign will either report it as missing (red question mark) or modified (yellow warning triangle). If it's missing or modified, ID insists you fix this; when ignored, it will use just the preview on print and export (the lo-res bitmap preview). You must have a real, live, up-to-date version of the original.
If you are making a modified copy of the original, save it and don't delete it "afterwards". There is no 'afterwards' -- every time you need to print or export your 'current' document, this copy is needed.
(Not meaning to be confusing, but it is possible to embed an entire image file into ID. People recommended against doing this, because it has no immediate advantages, other than that you or anyone else can't modify or delete it, and it will make your ID file much bigger and prone to crashing -- in which case you'll lose everything. In your situation, it's even a worse-than-worse solution, because you still want to be able to edit the 'image' -- that would mean un-embedding it, saving to a temp location; edit; update link; then re-embed. So don't do it.)