When I've gone to check on the girls the past few nights, this is how I have found them:
The first night, it startled me to see another body in Abby's bed.
They look so cute together but we've been moving Clara back to her bed in case they thrash about and kick and/or hit each other, as sleeping kids often do.
Last night, Clara was fussing and when I went in to check on her, she was in Abby's bed. As I picked her up to put her back in her bed, Abby said, "No!" in her sleep. Even her sleeping brain didn't want me to take her sister away.
Despite occasional bickering, they really are the best of friends. I love watching them play together and I really love when they go off to entertain each other and give me a break.