But didn't the eldest brother say his 9-year old sister went to a doctor and she remembered her mom walking her to the sister's bed at some point during the night? I think it is possible she never went to sleep. She laid down with her daughter until the daughter fell asleep and either a.) went back to the party or to meet up with whatever she wanted to share with her friend or b.) as she was laying with her daughter noticed her stuffy nose and decided to run out and get medicine since she was not sleeping yet anyways.
I may have missed more information. What I understand at this point is that Karen went home with her daughter and went to sleep/bed with her. When the daughter woke up the following morning at 6 AM, her mother was not there. I don't know anything about the children being in the same room in the morning or shopping for medicine. I understood that the 9 year old woke up at six and was surprised, or thought it unusual, that her mother was not still there sleeping beside her.
Do you remember where you read that both children were in the same bed in the morning? If the children were put in the same bed, why would the 9 year old be surprised that her mother was not there at 6 ... wouldn't Karen have slept in the other bedroom rather than squish three in a bed?