Hi, and I'm sorry to hear that your baby has oxalate crystals...I am not a vet, but have been dealing with stones and crystals with my baby for almost 3 yrs now. He has ammonium urate stones, but I have done research on calcium oxalate stones as well...Here is a link showing you a chart of foods that are low oxalate. You need to stay away from any foods that are medium or high oxalate because they will cause more crystals.
http://www.branwen.com/rowan/oxalate.htm
Calcium oxalate stones form in acidic urine, so you kind of want to feed more alkalizing foods. Here is another link with very useful information on that.
http://www.b-naturals.com/Dec2002.php Stay away from feeding kidney and organ meats like that.
Also, you need to feed foods that are high in moisture. You should be feeding equal parts of food and water if your baby is on dry food. Wet food is preferable because it helps keep the urine diluted and that's your goal so that she can try to pass these stones. The longer they stay in her bladder, they can start accumulating and making a much larger stone/crystal.
Encourage her to drink more water. You can also give your baby a juiced zucchini in the mornings to help get moisture in her, and it's a low oxalate food, so it's good for her.
Calcium oxalate stones do Not dissolve, so your best bet is to keep her urine diluted to try to help her pass these.