What information is provided about the author Saraswati Gangadhar and his connection to Shri Narsimha Saraswati Maharaj?

The preface in Chapter 0 explains the lineage of Shri Saraswati Gangadhar, the author of the Brihad Guru Charitra. His family surname was Sakhare. An ancestor, Shri Sayandev, received the grace of Shri Narsimha Saraswati Maharaj and was given a boon that his descendants would perform constant service. Chapter 0 clarifies that Shri Saraswati Gangadhar is the fifth descendant from Shri Sayandev, fulfilling this ancestral connection and service through his writing. This familial blessing established a deep-rooted bond between the author's family and the Guru whose life he chronicled.