Obviously they will not catch Sai, she will see their car stop and hide in her seat .
Spoons will think Milind is driver and Maduri is the malkin (or maybe Madhuri hides too) and decide that Sai is not doing peecha.
Then, they will happily go to see Daadu.
Sai might call Ashwini and tell her she went with her friend Neha to help with something.
But once they meet Daadu, they will know the note was fake, thats when they will figure out Sai was acting.