Yes and no. Encore doesn’t have a way to define what happens when you press the Menu button if you’re already on a menu. (I’m not even sure if that’s allowed by the DVD spec or not. Different DVD players may behave differently in this regard. You should test.)
However, there are two menu buttons on DVD remotes- Main Menu and Title Menu. They’re often labeled differently depending on the manufacturer or the player. The difference is that the Title Menu is a global setting and applies to all timelines and menus, so your users can use that. You may have to give them instructions, though.
You may be better off using invisible buttons that auto-activate, and put instructions on the disc for how to operate. “Press Enter to return to the menu, press right to advance to the next video, press left to go to the previous video.” Or something like that.