Correct, except that 2021 and 2022 Forms 5329 requesting waivers of the penalties for those years need to be filed as well. Nothing else needs to be amended on the 2021 and 2022 tax returns. The IRS has a history of granting these waivers. The only case I can imagine where the IRS would not grant the waiver is if the explanation indicates that not taking the RMD by the deadline was intentional.
The distribution of these amounts is reported on the tax return for the year in which the distribution occurs, presumably 2024.
And just to be clear (which you seem to understand now), you inherited immediately upon the death of your father. The date on which the rollover to an inherited IRA occurred is not the date that the 403(b) was inherited.
Inherited IRA custodians are not required to provide reminders and generally will not because it's possible for the RMD to be satisfied from another IRA that the beneficiary inherited from the same decedent that is subject to the same RMD requirement. Fidelity does calculate the required amount and will display the calculated amount when you initiate a distribution from the inherited IRA.
