Retirement tax questions

Since my father was alive when my brother passed, he was still a beneficiary.  My father passed two months after my brother.  My father's half was transferred to his estate account exactly the same as my mothers was to her account.  The difference is my father's estate had to then cash out his half while my mother can keep hers intact.

 

What you said is how I thought it worked - my accountant is telling me different.  He says I need to first do  a K1 with  my brother's estate 1041 to my father's estate (and my mother). I don't know what I would put on those K1s.  I thought the only K1 to come from this would be from my father's estate to my mother (according to his will)  of the cashed out 401K.  You confirmed this.  I guess I need to talk to my accountant.

 

Thank You