You might want to ask captainmilehigh if he can get you a dozen of the mini batteries next time he’s in Japan. Hell...he might just as well bring a plane full. He could probably sell them for 3 or 4 times the cost.
Good luck and be safe!
I trust you have your granddaughters permission on the air photography. She (or the groom) may now want/like that, and it could make guests uncomfortable (regardless of your intensions). This is all aside from the subject of flying over people.
And even with permissions. you don't want to be close to people, so the benefit of wide-angle photography from a distance might be very small to "not worth it" for wedding photography.
Most weddings have sound if outside. I've been at a wedding no one even knew a drone was there..and that was a p4p.. not a mini. But as far as flying over people thats a different story. And some drones have zoom. So.. no wide angle. I think most of its coming from traditional wedding photographers having a little competition.