That should just work as long as you have write access to the group. Also, make sure you're doing this in Zotero client, not on zotero.org.

Collections can not be copied within the same group.

Yes, there's no way to create a copy of a collection within the same library. It probably should be possible (via modifier key perhaps), but I honestly don't remember anyone asking before. The use case is also somewhat odd I think, and tags, rather than collections, probably fit here better. Do you mind elaborating on the use case so we can figure out if this is something that Zotero wants to support?

after the first time you drag a collection of a group to a collection of the target group, the collection that was dragged can not again be dragged to any other collection of the target group

That's sort of for the same reason as above. Making copies of collections within a library is not supported. Zotero thinks that you want to drag the same collection, which currently does nothing (I think. It may update items within that collection)

The behavior you're seeing is expected and I'm not really certain if it should change (dragging the same collection to a group library should provide some better feedback to the user, but I don't think it should create another copy... or maybe it should). Feel free to expand on your use case so we can better understand if this can be more broadly applicable.

So in this case you're not actually interested in copying items within the collection, you just want to replicate the collection subtree. I'll have to think about this, but I don't currently see how Zotero would support this in an intuitive way.

Hello!
Another question.
This is a corporate project that expands the use of Zotero.
As stated in the documentation of Zotero, there is no limit to the number of members of a group.
However, if this number is very large, and the total of the group Administrators also is large, is there the possibility of problems with synchronization, between Web base and local bases,arising from a large amount of concurrent updates?
Thank you.

No. The question does not refer to the possibility of simultaneous updates of the same object (collections or tag references), but to the possibility of many simultaneous updates of different objects, because the group will be unique.
The collections will be pre-defined and tend to be stable.
As for the tags of the references, they tend to be little changed, and each set of references belonging to a collection will be changed by a specific administrator.

As long as the concurrent changes are being made to different items in Zotero, you shouldn't see sync conflicts (keep the automatic sync on, so the syncs happen as frequently as possible).

a single tag is essentially treated like a single item: that is, if two users "modify" the same tag (i.e. add or remove it from items) on different computers between syncs, that causes a sync conflict. Rather than trying to let users resolve that, though, Zotero will add the tag to any item it's associated with on either computer. It'll display a message on sync.
That behavior will likely change in the future, but not sure when.

no, it's just a message that the tag has been added to items in all locations, not a dialog, there's not option to choose.

Hi!
Given a reference (item), can I find out which member of a group who registered this reference (item) in the group's library?
If possible, how?
Thank U.

the online display of a group has an "added by" column. It's not available in the client (Zotero Standalone or Zotero for Firefox).

If you have a "center" pane, you're looking at the Zotero software, where, as I say, this isn't available. It's only available in the group library on zotero.org.

currently no, for technical reasons, in the (foreseeable but not very near) future yes.

"after the first time you drag a collection of a group to a collection of the target group, the collection that was dragged can not again be dragged to any other collection of the target group"

This needs to change. I see no point in limiting this functionality. In my case, I imported a data pull (PDFs of articles downloaded) as the articles were downloaded. I'd like to keep that set in-tact, but duplicate it in order to use some of Zotero's functions, such as renaming from parent metadata, on a clean set, which I would rename to "data pull with renamed." But, now I'm stuck and can't drag the unnamed collection to the group or the renamed collection into my personal library.

Why limit this functionality? I assumed if it was possible once that it would be possible twice. Now I've wasted my time. Help?!

It's also obvious we're talking about voluntary, not involuntary, duplicates since the question involves dragging items.

I would suggest that involuntary duplicates should always be avoided and voluntary duplicates be always allowed. That way, the user--not the program--decides when something is duplicated. Is there a way to choose what function "dragging" an item to a folder performs - to choose to "move" an item instead of "copying" when you drag it?

For instance, dragging a PDF into another folder automatically creates a duplicate of it instead of moving it, which means if you really wanted to move it you have to remove the other one (major problem if you're dealing with a lot of files, which people using a PDF manager would be). So you can't actually organize your files as your would in any other file structure on a computer - which makes the functionality tough for new users, like me, to adopt.

In answer to the question about why my situation would involve a group: I have my own library and it contains the folder for this project. I also have a group for the project so that my project advisors can access the PDFs that I want to share with them. I wanted to put the same collections and subcollections in both places in two ways: One copy archived "as is" and the other "adjusted" using notes, rename from metadata, etc.

Some things in both my personal library folder and in the group for the advisors will need to be duplicated. This is currently impossible, so far as I understand. It would be lovely if it was as easy as a drag and drop - so I can keep my files in my library, but share a copy of them with my group.

Can you explain the export--> import you suggest for creating actual duplicates? I exported an RDF and can't get it to import.

For instance, dragging a PDF into another folder automatically creates a duplicate of it instead of moving it, which means if you really wanted to move it you have to remove the other one

that's a misunderstanding, btw. That's not a copy in the sense you're treating it. It's the same item in two different locations. So if you move it to the trash from one collection (as opposed to just removing it from the collection), it will disappear from all collections it's in.

But you can toggle that behavior by holding the shift (Win/Linux) or Cmd (Mac) key while dragging.