Why, baby, why?

For a week, we had cousins in from Seattle. An 8 and 5 year old. It was interesting because we rarely have any people at all in our house for any given time. It was noisy and chaotic. Ivy slept all night, every night. Would go to bed at 9 or so and sleep til 7. How does this work? Cousins left and she was back at getting up at 330. Last week, we welcomed another guest. At 9 or so, Ivy goes to bed and around 7, she gets up. Wow! I am liking this sleeping through the night deal. My boobs are even used to it. My question is, when our guest leaves, will she go back to getting up early? I don't think that I am going to like that much. Maybe I should make him stay so I can sleep all night.