I heard a story about Udi healing a very sick girl. Can you provide the details of this incident from the Satcharita?

Yes, Chapter 33 includes a footnote by R. Hari Sitaram Dixit recounting this miracle. A gentleman named Khimji Lalji Joshi had a daughter who was gravely ill and so weak that her limbs were like twigs and she could not walk. Her mother first obtained some of Maharaj's Udi, which gave the girl immediate relief. The family then traveled to Shirdi. As detailed in Chapter 33, the girl was so weak she had to be carried to Baba. Maharaj applied Udi to her and blessed her, and within a few days, she was able to start walking on her own. When she still had some difficulty getting up, Baba gave her a fruit to eat, which completely resolved the issue.