Welcome to the forum.
Unfortunately, PrE does not allow for supplemental Audio Tracks, when authoring.
I use Adobe Encore for this, but it is only available bundled with Premiere Pro. I do not know if some other, third party, full-featured authoring apps., like Sony's DVD Architect can do that, but I would suspect that they can. The specifications for DVD Architect should have that information, and as it's quite common in full-featured authoring apps., I anticipate that it has that capability.
If you do go with that program, our MOD, Steve Grisetti, has written a very good book on DVD Architect, and it's available at Muvipix.com.