1) There is no US filing requirement for your father as he is a nonresident and is not in the US.
2) Form 3520 is an information form only and not a tax form. It is a separate informational return sent to the IRS and is not included with your tax return. It is a return to report transactions with foreign trusts and receipt of certain foreign gifts.
You can download the form and instructions with the links below. TurboTax does not support Form 3520.
IRS Form 3520 - https://www.irs.gov/pub/irs-pdf/f3520.pdf
IRS Form 3520 instructions https://www.irs.gov/pub/irs-pdf/i3520.pdf-
