Does Chapter 10 say anything about Sai Baba's ability to change a person's destiny or affect their karma?

Yes, Chapter 10 makes a powerful statement about this. It explains that for a devotee who places complete faith in the Guru's feet, the Guru can metaphorically "strike a nail over the lines of destiny," which means he has the power to change one's fate. This is a profound assurance given to his followers. The chapter also directly addresses karma, stating that by the Sadguru's grace and even by his sight, a devotee's accumulated (Sanchit) and current (Kriyaman) karmas are destroyed. This shows that devotion to him is a path to overcoming the otherwise binding effects of past and present actions, leading towards liberation.