Open Windows File Chooser At Default Location

Is there any way of making the default directory location for application.getopenfilename work properly with shared locations?

Presently I use ChDrive then Chdir but I cant use ChDrive if workbook is opened from a link in email for example. Please see below

I have a VBA routine that asks the user to load an existing file on startup.

I want the window for the file selection to open at the same folder every time. (the folder is on a shared drive)

The workbook to run the code will always be located on this same share at a fixed location.

My present code builds the path to the desired opening folder by collecting the drive letter from the current working directory (which has to be done as everybody maps there shares to different letters here, its not guaranteed to be the same! )

then i ChDrive to this letter.

Then I ChDir to letter plus myKnowndirPath

This works fine, the window always opens at my required folder. But only as long as the user has navigated to the folder containing the spreadsheet and then ran it from there. Because that way a drive letter is available.

However i found that if i sent a link to the workbook or its home folder. And the user opens the link or a windows explorer from that link and then runs file from there.

Then it stops working beacause there is no local drive letter in the working directory path. i.e. working directory shows as

'network \shareddrive
ootafolderanother arget

instead of something like
J:afolderanother arget