I know that there is a tutorial available that allows you to replace the horrible background photo that comes onto your DVD if you merge 2 or more projects together.

I was wondering if it's possible to create a replacement photo that would be used by the program every time that you merge projects together without having to go through the steps currently involved with doing so. In other words just permanently replace with your default. If so how is this done?

Not possible as the default menu is within the program, but I get your point. What you want is similar to overriding a default template and have the program uses it instead. So, the program must be written to handle external background file for the merge.