you just add the additional audio track. It is as simple as that. DVD LAB PRO cna handle as many audio tracks as you want to and you cn also select, what is displayed, when they are chosen (English, French, German, Russian, etc).
You can add an audio selection menu or even add the audio selection to the main menu (like I did fo rmy HEAT edit). DVD LAB PRO lets you totally customize the DVD to do what you want.