What are the dual benefits of creating and studying a Guru's biography, as described in the context of Sai Baba's tradition?

Chapter 0 describes a symbiotic relationship with dual benefits in the creation and study of a Guru's biography. The Sadguru is said to accept two types of service through books. Firstly, the writer who composes a detailed biography performs a direct and profound form of Guru service. Secondly, by studying and performing Parayans of that work, other devotees also serve the Guru. This creates a powerful dual benefit: the author gains the merit of serving both the Guru and 'God in humanity' (Jan-Janardan), while the devotees who engage with the text are guided toward achieving the purpose of their own lives, fostering a spiritually enriched community.