If you have an attorney or executor for the estate, this could be taken care of this way.
First the Form 4972 is not needed.
It appears a 1041 Estate return should be filed for the 1099R, and it would show all the money distributed to the 3 heirs on a 1041 K-1 (that each of the 3 of you would get). The 1041 would have no tax due, and each of the 3 heirs will report the distribution as ordinary taxable income.
I would however talk to someone with tax expertise, to do this for you.
