Save workbook to sharepoint with dummy username and password if current user doesn't have access to the sharepoint

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We are working with a local excel file where everyone in our company can add data if they have the password of the file.
Now we need to publish a copy to a sharepoint site with only a few members having access to that sharepoint.
The sharepoint copy is needed for a power query run on it for online excel users (local power query gives errors)
is this possible to write a dummy member login in the vba code to upload/saveas everytime the file gets saved or closed?
the original file has to stay open if saved.