What is the relationship between the Brihad Guru Charitra and the Laghu Guru Charitra, and what do we know about the author of the former?

According to Chapter 0, the Brihad Guru Charitra, also known as the Thorale Guru Charitra, was written by Saraswati Gangadhar and is a famous, widely studied work. A separate and distinct work mentioned is the Laghu Guru Charitra from Wadi, which consists of only 707 verses and appears to be much older. The protagonist in both is Shri Samarth Sadguru Narsimha Saraswati Maharaj. Chapter 0 also provides details about the author of the Brihad Guru Charitra, stating that Shri Saraswati Gangadhar was a fifth-generation descendant of Shri Sayandev, whose family had received a boon from Shri Narsimha Saraswati Maharaj for their constant service.