One would be more than enough. If overtired mums can handle three kids, a professional nanny certainly can!

Hope you enjoy the wedding, we had dear friends get married when DD2 was 7 months and DD1 just gone 2 and I really wish I'd had that option. I basically missed all the fun and half the ceremony until the last hour when they were both asleep. If you can get a sitter and trust them, kick back and relax!