You could just reduce potatoes and mix them with something she doesn’t like. This is what I did. I mix swiss chard with some potatoes and they eat it this way. They get mashed potato but every once in a while. I am avoiding these foods now until we get some good flora back into my little gipsy (she has dark eyes and long black hair so this is where the nickname comes from, my other daughter and I are blue eyed blondies).
Yes, I don’t think we can take milk and cheese away or fruit. I did reduce the milk a little because my girls eat enough other high calcium items so they get one meal with dairy and kefir before bed time. One girl is borderline anemic second time already so then this reminds me to separate dairy from food that offers iron. I already fixed it with diet modifications once about year and half ago but then lost track of it since then and kefir at dinner time probably did it this time as well as cream or cheese with foods containing iron. Last check she was slightly below normal again so I remembered to watch out for that again.