Although both vaulters are at very early stages of development, they can probably be helped by focusing on the following:
At it's most basic element, the pole vault is a jumping sport. If they focus on only one or two things it should be to jump strongly off the ground without losing speed and reaching their top hand to maximum height just as they leave the ground to minimize the shock of the plant. Tell them the tip of the pole should be as quiet as possible as it makes contact with the box and the pole rolls into the pit to understand the jumping up aspect.
This needs to be done with a straight plant bisecting the face/body. If the pole is planted off to the side, all is likely lost.
As their coach, check their step to make sure it is as close to directly under their take off step as possible and adjust the approach as needed.
I sometime describe the vault to kids as though they are trying to dunk a basketball, but taking off from the free-throw line. Imagine how much speed and jump is necessary for this, but keep in mind timing of a tall plant is very important.
1. Straight, middle pole plant position.
2. Accelerating speed and JUMP at take-off with a tall reach and a good take-off step under the top hand.
3. Pick up the feet and make effort to turn.
4. Standards all the way back (required).
5. If the vaulter is hitting the bar quickly on the way up because they are jumping well, small increases in grip height can be made (2 inches at a time) to give them a little more time to get the legs up, but don't forget to move the start of the run back just a little if the grip is raised (my general rule at this level is to move the step back half as much as the grip is raised. (Example: if you raise the grip 2 inches, back the step up one inch from the prior jump with the lower grip).
Good luck. Hope this is helpful to all of you.
"Pole Vaulting...The Natural High"