K.B.
I have 3 children. They dropped their second nap at 15 months, 11 months, and 14 months, respectively. They all basically did what your daughter is doing-just played in their crib during one of the naps. The good news is that once they drop a nap, their bedtime can be a little earlier or wake time is usually extended. I actually enjoyed it , once they dropped their morning nap because then we could be out doing things all morning, and weren't constricted by nap time. Now my just-turned-5-year-old doesn't nap at all. The younger ones are still napping in the afternoon. It makes for a very long day with one of them not napping at all. I do make her have "quite time" somewhere in the house away from me or in her room. I see nothing wrong with your daughter having "quiet time" in her crib until her brother is ready to drop his nap too. Good luck.