Testing Other Grains

We believe baby girl has FPIES to oats. Her older five year old brother has confirmed FPIES with triggers of egg and cashews.

For parents whose baby has FPIES to a grain, if they reacted to another grain (rice, quinoa, wheat, etc) did they react the first time they had it?

Just trying to sort out what foods we can say are "clear" though we know it can take multiple exposures before a reaction occurs. Just wondering since they might be linked would she react to the first exposure of the new grain.