How to Amend Returns for Self-Employed Health Deductions

I retired in 2012 and have been working part time since then as an independent contractor (engineering consultant).  I just discovered I could have deducted the full amount of my Medicare Premiums and Qualified Long Term Care Insurance since I'm self-employed (yes, made more income than the total missed deductions).

 

Never had to amend a return before (Federal and State).  Unfortunately, I can only go back three years.  My questions.  Would appreciate answers for each rather than a generalized answer.

 

1.  I assume I use my TurboTax 2021 software to amend the 2021 returns, the 2022 software for 2022 & the 2023 software for 2023.    All three returns used TurboTax Premium. 

 

2.  Where do I enter these deductions in TurboTax under my self-employed status?   I'm guessing the answer may not be the same for the years in question.  For one thing, I don't recall seeing the IRS Form 7206 (Self-Employed Health Insurance Deduction) before the 2023 tax year.

 

3. Can I e-file the three Federal amended returns with TurboTax?  I believe TurboTax can't e-file an amended return for my state (Maryland) which is unfortunate.

 

4.  Do I file all the amended returns in quick succession or do I have to wait for 2021 to be processed first before filing 2022, etc?

 

3.  Why did TurboTax not find these deductions for me in the first place?  I thought there was a guarantee for 100% accuracy.  Flaw in the software's interview process or Forms?

 

Thanks for the help and have a great holiday season.