Pdf Merging Online PDF (.pdf) and Microsoft Word (.doc/docx) are completely separate and distinguished file formats. Simply pasting one to another would make your document look terrible and poorly formatted if that could be done. You CAN save a Word doc to PDF with Windows 10 to a print file document if you want a PDF document that anyone can read online. You will have to create a new Word document, convert your PDF to text and then combine the two for a complete report, article or story. You have not provided enough details about your writing project to provide a more accurate answer. If this is for reference, you do not need to include the PDF, just selected lines and use footnotes or end notes for source of your selected lines.
Please contact me if you need more research into your exact writing project, or need the specific PDF to include with a published story.