Unless you reported the contribution and deducted it then reporting it a s non-deductible contribution on a 8606 form will not change the taxable amount so there is nothing to amend.
The missing 8606 forms can be filled by hand and mailed in.
2018 form: https://www.irs.gov/pub/irs-prior/f8606--2018.pdf
2018 instructions: https://www.irs.gov/pub/irs-prior/i8606--2018.pdf
2019 form: https://www.irs.gov/pub/irs-prior/f8606--2019.pdf
2019 instructions: https://www.irs.gov/pub/irs-prior/i8606--2019.pdf
https://www.irs.gov/filing/where-to-file-addresses-for-taxpayers-and-tax-professionals-filing-form-1...
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
