One way to prevent your other kids from waking up is to put a white noise machine in their room so that they don't get started awake if they hear their sibling cry. If your 2 year old shares a room with a sibling, create a temporary sleeping arrangement where the sibling sleeps elsewhere—in your room, in another sibling's room—while your 2 year old gets used to sleeping without waking up crying for milk. Once your toddler has gotten used to it, then you can bring the other sibling back to their room.