Same food as when they were young. Maybe less of it if weight gain is a problem but it never was for us. If your older girl seems to be losing interest it might be a health concern with her, maybe teeth? Or sometimes folks have found the food manufacturer changed something and did not put it on the label and it puts the dog off.
That's a lot of Vitamin E, did your Vet ok that? Our own human doctor recommended my OH lower his IU to 200 a day, which would be much less for his weight than your dog is getting and she must weigh a lot less. Google it up, too much Vit E can be responsible for thin blood, poor clotting, and injury outside or internal might result in excessive blood loss.