In the first note, the one(s) who took Nancy, gave two deadlines to meet their demand of 6 million in bitcoin - one on Thursday at 5:00 p.m. and another with something worse happening if the demand was not met by, Monday at 5:00 p.m. They also stated that there would be no further contact at this time.
"Poof of life" was requested by the family. The first deadline passed without the perp(s) sending POL. This delay makes sense since they originally stated that they would not be in further contact.
The First deadline slipped by without payment. I believe this may have been a strategic move so the perp(s) would communicate further, with LE hoping that they would mess up, allowing LE to track them down.
Right after the first deadline, the brother made a second plea.
Hence the second note. There was no ransom demand in this note. I believe it is because this second note's sole purpose was to show some form of POL. Possibly something that only those close to Nancy would know.
Sidenote: Just some observations with the assumption that these notes are legit and are from the one(s) who took Nancy.
Have you not seen the latest plea from Savannah, sitting between her brother and sister, posted to her Insta ??