Form 926 is not supported by TurboTax and must be filled in manually. https://www.irs.gov/pub/irs-pdf/f926.pdf
To attach form 926 to your tax return, you cannot e-file and have to print out your tax return and file by mail.
Form 926 Instructions state you do not have to file unless you own 5% or more of the voting power of the foregin corporation.
https://www.irs.gov/instructions/i926
See "Exceptions" at the bottom of the page.