'The story belongs to the boy, but three other characters are played by Akshaye and two women, whom I'm yet to cast, play very important roles in the boy's life.
And the actor-director clarifies that he never thought of casting Darsheel Safary, who played the lead in 'Taare Zameen Par'.
'We've a short-list of 12-15 boys now. And no, Darsheel was not considered at all. I'm looking for a totally untried face,' Farhan told IANS.
'Akshaye's story is integral to the plot. Akshaye knows it's a very important part. Otherwise, he wouldn't do it. He is kicked by the script.'
Farhan starts filming 'Voice From The Sky' in November, though he reveals it was scripted right after 'Dil Chahta Hai'.
'Then there is 'Don 2' that will have all the actors from my first 'Don' including Shah Rukh Khan and Priyanka Chopra. The story and screenplay are done.
'I started writing 'Don 2' a few months after 'Don' released. So this year I only have releases as an actor. Next year I'll have two releases as a director,' said Farhan, who is making his acting debut with 'Rock On'.
Saif, who featured in 'Dil Chahta Hai', opted out of 'Voice From The Sky' a couple of months ago, but the filmmaker is not bitter.
He said: 'Both Saif and Akshaye are my buddies. I needed an actor of really good calibre, at the same time sensitive, sophisticated - a guy who seems extremely hard from the outside, but is soft from the inside. Both Saif and Akshaye fitted the bill. Saif didn't work out.
'There're many reasons why Akshaye works amazingly for the film. He is damn excited. He loves his role. And I love him in the role. It'd be great fun working with Akshaye again. Fortunately, all the actors I've worked with so far have been a pleasure,' said Farhan.