Glad you like the diagrams! If you haven't discovered it, you can click on the images to get a much higher resolution version that you should have no trouble reading.
Regarding the weight transfer--there's a reason your wife has trouble putting 100% of her weight on the outside ski in wedge-level turns. It's not necessary! And it would involve moves that are counter-productive, as I'll try to explain below. Furthermore, if she's just beginning, it would probably challenge her balance uncomfortably, at the very least.
(Please note that it is also quite possible that she is making defensive, braking wedge turns that are an entirely different animal than what I've described and illustrated. Defensive turns involve pushing the outside ski away, into a skid. Because you're pushing your ski away from you, it is almost impossible to balance on it at the same time, so defensive skiers very often fall to the inside ski. This is a deeper-rooted problem that cannot be solved with just a technical focus--ie. "put more weight on your outside ski.")
All of these diagrams show passive weight transfers--progressive shifting of the pressure toward the outside ski due to forces of the turn that pull toward the outside (like the weight shift of a car)--not due to any intentional, muscular movement of the skier toward the outside ski.
This distinction is more critical than you may realize. Obviously, experts move their bodies toward the inside of their turns ("inclination") as they balance against the powerful forces of high-speed turns on steep terrain. At very low (wedge turn) speeds, the forces are much, much less. To put 100% of your weight on your outside ski would require a movement in the opposite direction from what experts do--a "negative movement" toward the outside of the turn. It is no more necessary than it would be to tell the passengers in your car "shift left now so we can turn right." Because it is opposite what experts do, it is a dead-end habit that you would have to "unlearn" as you progress.
In terms of the previous discussion, then, the "principle" is smooth, sinuous movement of the body (center of mass) from inside one turn to inside the next. The amount of pressure, and its distribution toward the outside ski, are effects--characteristics that vary with speed, turn radius, and steepness. The diagrams show this. Note that the pressure does not shift 100% to the outside ski in wedge turns. Look at frame 12, where the turn actually begins. There is somewhat more pressure on the downhill ski, largely due to the tilt of the hill as the skier crosses it. The skier moves accurately inside the new turn (left, in this left turn), and the pressure moves progressively toward the right ski, passing through "50:50" at around frame 15. But it may never become 100% on the outside ski until speed picks up somewhat, in which case the skier surely won't be making wedge turns anymore! Consider which direction the skier would need to move in frame 12 to put 100% of his weight on his right ski. Uphill!--the direction opposite from where he's trying to go!
Here's a simple experiment you can do to show how critically important a misunderstanding of cause and effect can be. Part 1: Stand up, in an athletic, "ready" stance, like a football linebacker ready for action. Now, spring quickly to your left. Do it again, and note that every movement you make moves left. Note also that your weight shifts quickly to your right foot as you make your lateral move. Part 2: Stand again in the same ready stance. Now, shift your weight to balance on your right foot. Which way did you move this time? To the right, of course--the opposite direction of your previous movement.
So it is with weight transfers in my "reference standard" (default movement) turns. Weight shifts to the outside ski because of the turn. Weight transfers are an effect, not a cause. If you think you need to shift weight to cause the turn, it will result in completely different and inappropriate (for the purpose of these turns) movements.
On the other hand, none of this should suggest that you should never actively shift weight from foot to foot. Active weight shifts are "situational movements" that you must also master. You may reach "frame 12" in any of my diagrams, for example, and suddenly decide that you don't want to continue in the direction you're going, and you need to change your turn shape quickly. If you wanted to turn more abruptly left than the diagram shows, you'd either flex your downhill (left) leg or extend your right leg, either of which would quickly shift weight to your right foot and push you to your left. Conversely, if you suddenly decided to continue to turn right, you'd shift more weight to your left foot to push you back up the hill.
But by default, the silky smooth, sinuous turns depicted in my "reference standard turn" diagrams involve only passive weight shifts. You "let" the weight move to the outside ski. You don't force it.
Pretty technical, I know, but I hope it makes sense.