I think that for the most part I would increase the amount and variety of fresh raw produce so that they are getting them every day.
I do not feed any of my birds pellets and even if I did I would avoid Zupreem as they are known to use a lot of substandard ingredients. I do a cooked food that we call gloop on this forum, it consists of partly cooked whole grains, vegetables and thoroughly cooked white beans and lentils. There are several post on this food in the health, nutrition and diet section of this forum. I also feed fresh raw produce daily and a seed mix for their dinner.
Quality ingredients are not the cheapest, and I don't know how much leeway you have in controlling their diet or how much effort you are willing to put into it.