Ok ... so you will amend the 2020 return to show the repayment in full , then then amend both the 2021 & 2022 returns to remove the 1/3 payment completely.
All corrections are made in the 1099-R input section ... on the 2020 return you will indicate you do NOT want to spread the payments over 3 tax years. And the other tax years you will remove the indication that you had a repayment split. Nothing needs to be mentioned about when the repayment happened as long as it happened within 3 years of the distribution.
