My LOs tend to be very picky. Here are some things that have been accepted over this way that may help.
My DH makes ice pops out of smoothies. The kids LOVE them. Even with KALE in them
I think he uses bananas, pineapple, and strawberries to give it sweetness and yogurt, but you can use your own concoction.
Also, you can try adding prune juice to other things she will eat or offer prunes as they do seem to help with constipation.
DS had an issue with dairy and soy as a baby and did like almond and coconut based yogurts. Not sure if that would be helpful. You can add fruits she likes to the yogurt if that helps with the flavor being different.
I once made a pumpkin puree based sauce for pasta that was pretty good. Might be worth a try?
I used a powdered probiotic by culturelle I think it was that did not contain dairy and needed to be refrigerated. I liked that I could add it to anything I wanted. Applesauce, yogurt, juice, water, milk.....just drop in and stir and it didn't really affect the flavor.
Sometimes, not often, I will bake some muffins or make homemade granola bars. I know it has the grains you are probably avoiding, but you can add a lot of other things in that can be helpful. You can make blueberry or other fruit based muffins, you can add fruits and coconut and things like that to granola bars. Not sure if that would be helpful at all but my two seem to like that type of thing.
Another thing is, if I don't put food on the kids plates but I have it prepared or just out on the table for anyone to have or just on my plate they are often more likely to try it. And as deb said, if they help prepare the food they are more likely to try it as well.