We’ve been to two weddings recently where baby stayed with us and slept in her bassinet. I’m guessing by July baby won’t fit, but could they stay with you and be lay down in a stroller. We also didn’t stay all night, we can’t home about 11 for both weddings.
Whenever we've been to weddings we've sent one person back to the room with the baby for bedtime while the other stayed later. With our first he would take formula so if it was my friends wedding I'd stay later, and if it was his friends wedding he'd stay out. My youngest is purely breastfed so I'd always draw the shortest straw this time but thankfully we've not had any weddings! I really wouldn't leave a baby alone - think about Madeline McCann 🫠