You wrote: "Finding Fee for Service Turbotax help for prior year taxes.
How do I find tax preparation experts to help on a fee for service basis to file taxes for prior years using Turbotax?"
Be careful. You are posting in a public Internet forum. Someone could try to scam you.
That's an unusual request that you are restricting tax professionals to TurboTax.
We don't know exactly what you are wanting to do and why. There must be more to your story.
TurboTax personal products are not licensed for use by paid tax preparers. Intuit does have some professional tax products that tax pros often use.
If you have multiple past years to prepare and require tax preparation experts, have you tried to find a local reputable CPA/EA to assist you? Friends and relatives, work colleagues, your church, etc. might be a source of recommendations.