Thanks to both @Anonymous and @nexchap for their comments. I immediately saw I problem I should have recognized in 2014 after receiving the first (2013) K-1. The acquisition date which should have been my late father in law's DOD (and I'm sure corresponding cost basis) as recorded by Buckeye was off by a month. So, the date of acquisition on the 1099-B is correct but wrong on Buckeye's records. I guess at the least the K-1 Part II block L data from 2013 through the final 2019 K-1 is wrong! I just spoke to Buckeye and they said they will correct their records however, they can only issue an amended K-1 for 2019. I'll see what changes they have made when I receive the "corrected K-1". I suspect this is not going to be pretty as I've never done more (or know how to do) more than just transcribe K-1 data into the TT interview and then add stuff not asked in the interview view using the forms view. All previously submitted tax returns were accepted without reaction from the IRS. I fear that the fee to be charged by a competent tax preparer for such a complex issue as this will substantially exceed the dollar value of any errors I make in working this through on my own with TT and your already provided collective guidance. If IRS is unhappy, my perception is that they will provide the correct numbers and the penalty fee will be a small fraction of what the tax preparation fee would have been. UGH!
