The Roudybush she is being weaned onto is an awesome staple-diet for her, it's every bit as good as Harrison's for her, so if that's what she is coming to you eating as her daily staple diet, then honestly I'd keep her on it...You'll at least need to order some to feed her while you gradually transition her onto some other daily staple diet, like Harrison's. Both are great choices that are low in fat, high in protein, and high in overall-nutrition for her.
As long as you know the Nutriberries are only treats and not the food you feed her each day, and she's getting them during her weaning as her treats, then I'd just order them too and freeze them (it's usually cheaper if you buy them in-bulk or in the larger tubs in the case of the Nutriberries). So you know that she likes them as treats already, so it's probably better to buy them in the large tub and freeze them...But be sure to find out what variety of them she is being given as her treats because there are a bunch of different flavors, and they love some of them and refuse to touch others, same thing with the Nutriberry "Avi-Cake" treats, my guys love some of the flavors and absolutely hate others and won't go near them...Spoiled they are...
It's pretty awesome your breeder is weaning their babies onto Roudybush as their daily staple diet, it's a great choice and rare to find a breeder who is willing to spend the money to wean them onto either Roudybush or Harrisons. So that's a good thing for sure...