I found that I had to have DD sleeping in the living room (I also used to be quite strict on the dark quiet room for a nap for DS).

DD wound up sleeping a lot better, despite all the light and noise, she would come into her light sleep, kind of crack her eyelids open to see us and then snuggle back down for another sleep. And DS wouldn't be left alone to entertain himself or start calling out for me while I was resettling her. It was just way too hard running up and down the stairs all the time.

I think she was about 5 months when I started putting her in her room for her naps, when she was becoming much more aware of her surroundings and they were starting to wake her up rather than soothe her back to sleep.