Excel overwrite itself.

Can this be achieved...

I am trying to fully mimic an app but using Excel.
When you run a program it sometimes tells you a newer version is available for download.
I have replicated this inside an Excel file.

In the file open section, a macro looks on my website and compares its current version with a version text from my site.
If the versions match nothing happens, if the website has a newer version a message appears letting the user know.
When the message appears, another macro silently dumps the files user data & database info into a safe backup file.
Then....
You download the newer Excel file and overwrite the old Excel file.
When you open the new Excel file, it knows its new so silently opens the safe file and imports its data back.
All done, the file can then work as before but with a load of new features / bug fixes etc.

My question is this:

When a newer version is detected, the downloading and overwriting process has to be done manually.

Is there a way to make this work seamlessly?
Can vba within an Excel file, download a file with the same filename, close the Excel file then overwrite itself?

Any help even if its to say not possible would be a help.

Thanks

No. If the file closes, Excel closes, and no more code will run. This would have to be done using an external application.