I understand that a Jewish wedding primarily requires a ketubah and two witnesses (and, obviously, the bride and groom). In that case, are the witnesses (and not necessarily the rabbi) the "officiants," or is the rabbi considered the wedding officiant? May a non-rabbi officiate where a rabbi would normally officiate? I ask concerning a wedding which will be unable to include a rabbi due to coronavirus matters. I'm not asking about US state law, but rather halakhah.