At 10 months old she doesn't need that bottle. It is a prop really in the sense that she has learnt to have a full tummy to get back to sleep, the 5.30am bottle is the same really - she should be going longer than 4.5 hours at this age. I would start reducing the first bottle by 1oz every 3 nights to gradually reduce the amount in her tummy, when it gets down to a couple of oz you can just offer water and resettle. You can do the same with the 5am bottle or just resettle her until a time you want to be her wake up time.
We did this with my DD at 8 months, she didn't have a DF and was eating well during the day so those night calories aren't needed. She didn't like it when we just offered water but she stopped waking after a couple of nights. We treated every waking before 6am as a nightwake and resettled without feeding, after 6am was ok for a wake up time.
What do you think?
Laura