This had been working great. Baby would go to bed and to sleep at 7.20, dd1 would have a story downstairs and then go up about 25 mins later. But dd2 now won't go to sleep until sister comes up, and then they keep one another awake, messing about. It doesn't matter for the baby, as she has big nap in the middle of the day and gets plenty of sleep, but DD1 needs about 12 hours sleep and is consistently getting less than that. It makes her badly behaved and difficult, amongst other things. DD1 will sometimes sleep a bit longer in the mornings if I can get DD2 out of there before she starts shouting for milk.
Is there anything I can do to make this work better?