I shot weddings for years on medium format, when there were no zooms available. Then one lens, a zoom, changed life for me in a very beneficial way! While I used to have to carry the medium format equivalent of 24mm, 35mm, 50mm, 100mm, and in the bag, I could mount a single zoom, and only change lenses if I wanted to shoot tight couples portraits or wide scene-establishing shots.
In APS-C 'pro wedding kit' I would have 17-55mm for most shooting and mount 70-200mm lens for shooting from longer distance or doing portrait shot, and put 11-16mm for scene-establishing shots.
In FF 'pro wedding kit' I would have 24-70mm for scene-establishing shots and most shooting, or 28-75mm for most shooting as well as couples portraits (and a 24mm for scene-establishing shots), and mount 70-200mm lens for shooting from longer distance.
Of course, as a pro, just about everything was brought (many items in pairs), and what I listed above constitutes only the 'working kit of lenses'.
For a guest bringing a camera, for APS-C just mount a 17-55mm lens for receptions, use a 100mm f/2 for longer distance in the church. And enjoy yourself, and keep your shooting to the things which complement what the pro shooter will be capturing.