popa_bar_abba: While it’s true that we name the eidim involved, I have never seen or heard the words “to the exclusion of …” (or something similar) being stated, which implies that anyone *close* enough to the Chupah (and clearly not related to chosson & kallah) are witnessing the event.
It could be that that “loophole” is used when a Rav is marrying two people who may not be shomer shabbos (the “eidim” are not known to be shomer shabbos, either), particularly in outreach contexts, etc…