Upon rewatching 2x15 (for the nth time now), something came up to my mind. When Annalise wrote a letter to her baby and buried it, she said that the baby's name was Sam. Could it be possible that she also wrote something in it as her message to her husband, Sam, and how she was so sorry that he was killed or something that mentions the Murder Night #1? (I also think Annalise being apologetic or regretful is fitting at the time, since she just knew that Sam did not actually kill Lila Stangard which was the reason why they were okay with offing him, and though he told Frank to do it, Annalise did not know it at the time) I just thought that if that was the case, then the letter can be found and everything will be revealed. But I also thought that Annalise won't do it since she is cautious about everything, so maybe it's not really happening.