How did Sai Baba prove he attended Dev's Udyapan ceremony, and what was his disguise?

According to the account in Chapter 40, after Dev complained to Jog that Baba had not attended his Udyapan ceremony, Jog presented the matter to Sai Baba. Baba proved his attendance by revealing details only a person present could know. He explained that he had attended in the guise of a Sanyasi. He recounted how he first appeared alone, was invited by Dev to return for the meal, and then came back at noon with two other people, just as he had promised. Baba's detailed account to Jog served as proof of his omnipresence and his fulfillment of the promise to attend the feast, even though he was not in his physical body from Shirdi and went unrecognized by his host.