Hi, Joe.
What you'll want is a plugin built specifically for P3D, as VoiceAttack is not built to support any particular game or app. Outside of that, you'll maybe want to add a voice command to switch to your other planes... that may end up being a lot of copied commands between profiles, or you can create one profile that has all the switching and, 'include' it from each of your profiles (note: In the coming weeks, the referenced profiles will be replaced with multiple/stackable profile references).