If I understand you clearly, you need both to convert VPE to PDF and add some content from other PDF as well? All the VPE version right from the 3.5 allows doing the export of the data to PDF file. But in order to merge it with the content from another document you need an editing tool with a merging feature, I would suggest this one https://ds11.pdffiller.com but consider that it works best starting from the version 6, other ones could be unstable