Although the inherited IRA is now maintained for your benefit, the inherited IRA is still an IRA of which your father was the participant, not your own IRA. As such, it is entirely independent of your own IRAs. Nothing about the inherited IRA goes anywhere on the Form 8606 used to report your own nondeductible traditional IRA contributions and Roth conversions.
If your father had basis in nondeductible traditional IRA contributions, the taxable amount of distributions paid to you from the inherited IRA would be calculated on a separate Form 8606, a form that would have to be prepared outside of TurboTax. Otherwise, the taxable amount of any distribution from the inherited IRA is the entire amount of the distribution.
