I doubt that with no useful information, that ebay would be any wiser thsn you are.
Returns should be sent by tracked mail, and proof of delivery to your address, even though wrong address, would be sufficient for a buyer to get a refund, so any seller responsible would still end up being forced to refund without getting items back.
Do the parcels have a senders address, if so just mark as not known at this address, and put back in the post.