@julian @rimu @andrew_s @melroy @BentiGorlich @nutomic @angusmcleod say I make a video and post it somewhere I can set comments subject to approval. A forum or link aggregator whose moderation I trust posts a link to my video. I think I would like to approve a whole discussion that I am confident is moderated appropriately, but not all discussions, and also treat my reactions to individual comments as approvals for display at the publication site.
So I think I would want granularity, deciding whether my content is linked or cross posted, and whether I want to treat the remote discussion as a cross post to my comments section. But I would definitely want it to be the same object. In as far as I would have any duplication the cross post would be best thought of as nested under the post object.