That's an extract+specialty grain kit, not a partial mash. All the starches in those grains have been converted to sugar already, so all you need to do is steep them to dissolve it into solution. Your flaked barley, on the other hand will need to be mashed since it has no sugars in it. And thus the recipe would become a partial mash. Since FB can't convert itself, you'd need to mash it with some 2-row at about 153F for 45-60minutes, then rinse the sugars out of it.
You could add about a pound of FB to that recipe, but you'll be okay without it.
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