If this girl is only 9 months, is she napping in the am and pm? Cuz, wow, an hour each time? I agree with everybody else, this will become unmanageable real quick. At 9 mths, there is no reason she can't learn to sleep on her own. But you are the one who has to insist that is the only way you'll do it. It is for her own good after all.

If she will be sleeping in the same room as the others, I would suggest you start the CIO now, so when the others start, she's at least part way there.