Thank you, that link solved it!

Would there be a reason then that it doesn't work running a macro in Excel? I have the excel vba as shown below, it will open the source document, but won't run the word macro. But if I run said macro directly through word it does fine. I tried finding a solution, but from what I can tell it should work?

Sub Create_Mailmerge_PDF()
Set appWd = CreateObject("Word.Application")
appWd.Visible = True
appWd.Documents.Open Filename:="C:\Users\j***\Source Doc.docx"
appWd.Run "Mailmerge_PDF"
End Sub