Refeeding- any negative side effects?

I would love to know other’s experiences refeeding, particularly those with digestive issues or food sensitivities. My 6yr old daughter has been on the GAPS diet for over 3 years, sugar free for 2 years (due to candida issues) and now on a food rotation diet as well. Although we saw a lot of improvement, she has developed a lot of food sensitivities since then, plus the typical characteristics of a low metabolism. My question is when refeeding is it better to slowly add starchy foods (and test them out) or jump in and add high carbs straight away. Experiences please?