If she is not used to eating a variety of foods, it will take a bit of time to get her used to it.
Keep persevering with the offerings of fruit and veg. I am sure she will eventually start to eat more over time.
You could try removing all food late in the evening so she is hungrier in the morning and offer her a small amount of fruit and veg maybe for an hour or so before giving her any other food.
You don't want to starve her but to make her peckish enough to want to try the fruit, that is why morning could be a good time. Food has been digested all night and she would be eager to try things on an empty stomach.
All my ringies love corn, peas, apple, & grapes, (seeds removed for both). I pick garden grass for them and they love to chew on the juicy part of the stalk. Just make sure no chemicals have been in contact with grass.
Another thing you could try is thread the fruit and veg on a fruit kebab or skewer that hangs inside the cage. The bird can forage in a more natural position. Might entice her to eat if it is hanging in her face.
Is she an indoor or aviary bird?
Could try eating in front of her and if she looks like she is curious with what you are eating, offer her some or if she doesn't take food from hands, leave a piece on the top of her cage or in the bars.
I am sure when you get your new tame bird, it wont be long before she is taking an interest in the goodies the other bird is receiving and eating.