I started the 2018 return with an incomplete imported version; I need to replace the import with a complete PDF version of 2017 return, how do I do this?

I am almost done with the Federal.  The imported version of the 2017 extension to file is straight from a TurboTax Premier downloaded program; I started my 2018 return with the downloaded version of TurboTax Premier, and the PDF is from a completed file from an accountant (unknown software).  I do NOT want to have to start over again on my return--the differences between the incomplete version and the PDF are minor.