The previous answer from @DanaB27 doesn't address this question at all, but is instead about getting the 1099-B data into TTax for tax preparation.
TurboTax only allows upload of one file with this e-File process, so the challenge here is that's the file you designate to upload with the signed Form 8453-FE. If that is a PDF file, you can use a commercial PDF editing program to insert or append the 1099-B pages to it, but you must do this before you designate it for upload. There isn't a way to upload a second file or any file after you've submitted the e-Filing, and the TTax software doesn't tell you about this when you're doing your e-Filing, even though you may have checked the box(es) to enter summary amounts for 1099-B data.
