Hi Jacobo, and as far as your actual script goes, a version that does it is attached here.

To use it, put it in some folder say for example c:\scripts and then set up a shortcut key and put in the full path to the .js file as the command name, so if the script is in c:\scripts for this one put the command name as:   c:\scripts\DoMultiSave.js

Then when you trigger the shortcut key it will execute that script and you can look into the script to see how it gets the current file name and replaces the file extensions and then saves out the other file types.

When you do a "Save As" of a non-3DM file type it generates the file but it does not become the current file name of MoI, since those other file types do not necessarily store all of the information that MoI can generate, only 3DM files actually save your whole project data including various stuff like your viewport setup, background images, etc...

- Michael