S.H.
15 months is a growth-spurt time. And she could very well be hungry, as a result. Both my kids went through that too.
If you give her a bottle/milk during the night, the just have her drink water from a sippy after, or keep it in her crib with her. So she can help herself to it.
OR, you wipe her teeth with a moist washcloth afterward.
Lots of kids, will drink milk from a bottle only. It has a nipple... like M.. It is an instinctual thing... not her being spoiled. Milk comes from a nipple... its natural and normal for a child to have this instinct. There is plenty time to "wean" her from it later... if at night, this is the only time she wants a bottle.
The thing is, growth-spurts and hunger, does occur. Every 3 months is a growth-spurt in babies/kids. Thus, their intake needs INCREASES as well, even at night.
Try also to make sure she is given her milk before bed, and make sure she is eating and getting enough milk during the daytime too.
Both my kids, had GINORMOUS HUGE appetites, at growth-spurt periods. Like clockwork. I always fed them at these times.
They needed it. A growing baby/child has growing appetites. Even a Teenager goes through this too. They need it for development and brain development too.
Each child is different. Don't gauge it on your other kids and what they did. Some kids just metabolize food/calories quicker too, thus they get hungry more often.
All the best,
Susan