If she's hungry in the night then obviously she needs feeding. I wouldn't offer milk unless it's been at least a proper time since the last E. I'm assuming she was fed just before S at 9pm so doesn't really make sense she is hungry for a full feed at 11pm
Is she feeding enough in the day do you think?
Most people don't worry and feeding to sleep at night unless it's a prop. If your sis waits until a full feed time has passed and knows LO is hungry then it's not a prop it's just hunger.
Sounds like you've made great progress in the time you had and LO is sleeping great naps now
