Once retitled with your name as beneficiary, the executor can't take the RMD from an IRA you inherited, Only you can do that.
Since your sister took the total amount of the father's RMD, the requirement is satisfied.
See IRS Pub590-B for the info on how to calculate the RMD.
The rules for newly inherited IRAs are different since 2020.
Reply back if you need more details
You can rely on info from @dmertz
@elvisimpersonator
