Each tax return and each tax year is separate. There is no place on a 2022 tax return to say you are still waiting for a refund from a previous year. Dad should just file a correct return for 2022.
Your post is a bit confusing. You say your father filed incorrectly for 2020. What happened with his 2021 return? Was that also incorrect? What tax year did he amend? Amended returns take a vey long time to be processed. It is not uncommon for an amended return to take six to nine months or even longer to be processed by the IRS. Have you checked on the amended return site:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1
Another thing to try if it has been even longer than you indicated.....the Taxpayer Advocate.
TAX ADVOCATE
At the following IRS website, find the USA map and click on your state, and it will give you the number of your area's IRS Taxpayer Advocate.
http://www.irs.gov/uac/Contact-a-Local-Taxpayer-Advocate
Also see this article for more info on how the Taxpayer Advocate Service works::
http://www.irs.gov/taxtopics/tc104.html
https://www.taxpayeradvocate.irs.gov/wp-content/uploads/2020/08/TAS_CaseCriteria_061120.pdf
https://www.taxpayeradvocate.irs.gov/can-tas-help-me-with-my-tax-issue/
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
