When we copy an item (record), we do not duplicate it, rather we symbolically link the actual item in My Library with the "copies" in other collections, or this is my impression what Zotero does. Changes we make on one of those items are directly visible on other "copies." It would be very useful if we could do the same with collections and subcollections.

Currently, we cannot copy collections but can move or duplicate them. Any new addition of items into a duplicated collection should be repeated on all duplicates. This approach is very error prone (one might not be able to remember whether any other duplicate exists or how many duplicates there are) and very difficult to manage.

Best,

--mehmet

PS. This is related to my earlier posting titled "many-to-many relations," but the current suggestion is simpler and hopefully clearer.