Can you narrate the story of how Sai Baba attended Dev's Udyapan ceremony in disguise?

Certainly. When Bala Ganpat Dev invited Sai Baba to his Udyapan ceremony, Baba promised to attend. However, as the events in Chapter 40 unfold, Baba chose to test Dev's perception. He first appeared alone in the guise of a Sanyasi before the meal. Later, as promised, He returned at noon with two other companions to partake in the feast. Dev served them well but failed to recognize Baba, his mind clouded by delusion. After the event, Dev felt let down and wrote to Jog. Baba then revealed the truth to Jog, explaining that He was the Sanyasi, thus proving He always keeps His word, even if it is in an unexpected manner. Jog relayed this to Dev, who was filled with remorse and love upon learning the truth.