Shih-poo puppy who is a very picky eater...?

I have a 9 month old Shih-poo puppy who has been a very picky eater since I got her. She is feed 2x daily now on Royal Canin Puppy 33. I give her about 3/4cups 2x a day. Her first feeding is at 7:00 and her last feeding is around 5:30-6:00. Sometimes she would go the whole day without eating and then she would be famished the next day and want to eat constantly. I brought this to the attention of the owner of our local PetValu store and they had mentioned to me to buy a dog pumpkin mix and add about a tablespoon of that to her kibble. I have been doing that for about 3-4 days now and she just totally loves it. However I only give it to her at her night time feeding. What I am noticing is that she will only pick at her breakfast feeding. My question is would it be safe to mix it in the morning and evening feedings? If so, is it safe to do daily or should I only do this every couple of days?