What if she doesn't leave anything at all? My guess is that 23 oz of fluid is quite much for a night's cycle, does she leave in a hot weather? that would be one explanation...
Nop, no milk for lo to suck at night. Bad for teeth and molars are out or popping during that age, so it is a bad time to have the bacteria around. Why was she concerned about it? is her lo asking for both of them or she was thinking about leaving them just in case? diluting milk until it's plain water is a good tip, also just offering water for night time, if she leaves the option (i.e . water and milk) lo will go for the milk, no doubts!!!!!!!!!