All cameras should have been recording audio. Syncing by visuals, without a reference point (eg. timecode, a slate or a clap), is nearly impossible.
But a wedding doesn't have to be strictly real-time. If there is no sync point available, you might want to consider just cutting it like a narrative and syncing moments in broad strokes. I don't see a point in frame-accurate syncing, since that would result in sluggish pacing anyway.
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