Even although you don't need to match the carbs your child eats agains the insulin you're injecting I would still take the opportunity to learn to carb count. There quite likely will come a time in the future where you want to change to a basal/bolus regime and need to carb count. But even whilst you're using the mixed insulins it would be useful to keep each meal to a fairly consistent number of carbs. For example, if you have a low carb breakfast one day and then a high carb breakfast another day you may find problems with highs or lows because the same amount of insulin is injected each day but not the same amount of carbs are being eaten. If you can be aware of this then it will be easier to try and keep some consistency which would result in better control. Does that make sense?