first you have to start your amended return and then access the 1099-B/8949/capital asset sales worksheet where these sales are reported. if you imported, I'm not sure Turbotax allows changing the cost basis or entering an adjustment but you can try. Your broker is incorrect in reporting your tax basis to the IRS (BOX A) because it does not know it as you can see by the sales schedule. Maybe latter it issued a corrected 1099-B. the sales should have been shown as BOX B (tax basis not reported to IRS).
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however that's a technicality that I wouldn't mess with unless the broker issued a corrected 1099-B,
The IRS does allow making adjustments when the cost basis reported to it is incorrect. your adjustment amount is 22671-19613=3058. what you are doing is reducing the reported gain. thus the adjustment is entered as a negative amount to reduce the reported gain to 1139 (4197-3058).
to allocate the adjustment - number of share reported as sold on the line divided by total shares sold) times -3058. use adjustment code B which tells the IRS the tax basis reported is incorrect.
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i don't know if you what version you're using. if you switch to forms mode (desktop versions only) go to the k-1 disposition link. when that page opens see what is said about reporting sale of PTP/MLP. in short it says to use zero as the sales price (line 5) and basis (line 7). This is correct in your situation because there is no section 751 gain. it's incorrect when that situation exists. For the amt column use 0 as partnership basis. there is no gain or loss to be reported in this section. Everything is through the form 8949
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Turbotax asks for info that is not needed and is not used by the program. Some can be skip by clicking continue. other info even if not used can't be skipped (bad programming by Turbotax) However, if you aren't sure what those are, then it's better to answer than skip something that might be important. Such questions do not exist in the apps used by tax pros.
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you are correct that reporting PTPs/MLPs is a royal pain in the neck even for tax pros.
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the real nightmare is investing in one that just invests in others. you get one master k-1 and also a k-1 for each sub partnership. Had one case where there were 50 sub k-1s. The rules say each is to be separately reported. so that's 50 separate k-1s and a bill to the client to match.
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if you imported and Turbotax won't let you enter the adjustment. then try deleting those entire lines. you then have to use the capital asset sales worksheet to manually reenter the necessary data
