How do you modify existing PDF drawings in visio?

Microsoft Visio can only work with diagram file types like .vsdx or .vsd, so you can't directly edit a PDF drawing in Visio. There are, however, two common ways to do this:

1. Change the PDF to a format that can be edited

You can use Systweak PDF Editor to change the PDF drawing into an image or Word/Excel file. After that, you can import it into Visio.

If the drawing is scanned, you can use Systweak PDF Editor's OCR (Optical Character Recognition) feature to make the text editable first.

2. Add PDF as an object to Visio

To embed a PDF in Visio, go to Insert, then Object, and then Adobe Acrobat Document.

You can't fully edit the PDF inside Visio with this method, but you can add notes or draw on top of it.