You don't really need to move your other characters. Just move up so the herb is on either side of you, and use a key that does two things:

1. Sends the in-game keybinding to setview so all your alts have the same camera angle, and
2. Sends the in-game keybinding for interact-with-target.

I hit it five or six times while I move my mouse around over where the herb is. In this way your toons don't move and there's no chance one of'em won't loot by accidentally right clicking on the ground next to the herb.