Bonanza - Book 1 -"The Fight for Sarah"

Sarah Elizabeth Cartwright is the nine year old cousin to Adam, Hoss and Little Joe Cartwright.
Her Pa, John, the younger brother of Ben Cartwright, was killed the previous year in the line of duty, as the Sheriff of Carson City, Nevada. After her Pa's death, Sarah's Uncle Ben and his sons took her into their home, and lives.
Ben is very concerned to find out that his niece has recently been shadowed by a man in town, and at her school, claiming to be her 'Uncle'. The worry of a custody battle for Sarah, and a 'truth that is told', shakes the Cartwright family, to its very core.
These stories make the most sense when read in the proper order. Book 1, Book 2, etc.