It can't be done. They scrape the pin and upload it as your own, then change the source URL. It's not like they can magically change source URL. If you can't do it manually, it can't be done on auto too.
I think we already talked through support system about this, but just so other know. This option will assign Source URL that you set to pins pinned through that campaign. However, that's not repinning, It's pinning.