change Joomla menu shown in horizontal main menu

[oxfordhousebcn]

I would like a different menu than my Main Menu in Joomla to be used in the main horizontal menu in the template. What would I need to change in which file for this to happen?

I ask because I have a site in multiple languages and need different sets of pages to have different main menus.

Right now I have two templates installed, and have the second template assigned to all the pages in the second language. Ideally I would like to alter the appropriate files for that second template so those pages show a different main horizontal menu, because my Joomla Main Menu is in the first language.