What is the statement of personal or family history hearsay exception, and does it require the witness to be available?

Hypo 1: Bob claims he's entitled to an inheritance from his great uncle's estate. He presents a statement from his late mother, who had mentioned in her diary that Bob was the favorite nephew. Result: The statement about the family relationship and Bob's position as the favorite nephew, written by Bob's late mother, can be used in court under the hearsay exception for personal or family history, even though Bob's mother isn't available to testify.

Hypo 2: Sam is in a legal dispute over the ownership of a piece of land. He uses a letter from his deceased grandfather that details the family's possession of the land since his birth. Result: The grandfather's letter can be admitted as evidence under the personal or family history exception to the hearsay rule, despite the grandfather being unavailable to testify.

Hypo 5: Bob is being sued for a contract breach. He tries to use a statement from his late father about a business deal unrelated to the contract. Result: The father's statement is not admissible under the personal or family history exception because it doesn't concern Bob's or his father's personal or family history but rather a business transaction.