What happened is that the IRA inherited from your husband was trustee-to-trustee transferred to an IRA of your own before you did the Roth conversion. Such a transfer is not reportable, so the only Form 1099-R that you received is the one for a Roth conversion from your own traditional IRA. When TurboTax asks the horribly worded question, "Did [you] inherit the IRA from [financial institution]," answer No because the distribution was made from your own IRA.
