How to disable save with the same name

[Nelson78]

Hello.

I need a help to prevent other people saving on the master file.

The approach is the following:
1) Clicking on the button "Save", I need the pop-up "You're saving with the same name" and stop the operation;
2) Clicking on the button "Save as" without changing the name, then pop-up "You're saving with the same name" and stop the operation;
3) Clicking on the button "Save as" changing the name, it's ok;
4) Set a sort of secret combination of buttons to let me saving (example: ctrl+s)

Thank you.

 

[Nelson78]

Putting into practice, one more requirement is needed: the users have to be in condition of saving just one particular sheet on the master workbook.

Example:

3 sheets (alpha, beta, gamma) in the workbook ypsilon
for saving entire ypsilon, the users have to save with a different name
but the users can save in ypsilon the change done in sheet beta without using a different name (i'm imagining a new code linked to a button on that sheet "Save this sheet")

I'm not sure if I made it clear enough.