I have been assisting my dad with his turbo tax filings for several years, he just passed away and hadn't filed his turbo tax file. How can I submit for him?

I do not use turbo tax for my own taxes but have purchased and assisted my dad in filing his taxes for the past decade.  We had started his return but then he got ill and recently passed away.  Can I complete his return as if he is filing and submit for him, or is there a way to complete a return for him in which I state I have prepared for him?