Girls, we give them 6 months of lactose-free porridge, eats only if yo…

Girls, we give them 6 months of lactose-free porridge, eats only if you add a mixture, we're exclusively breastfeeding, what mixture should we take? Do we need 2 scoops after 6 months? Or is there a difference? We put one measuring spoon in the porridge, and another question when did we start giving milk porridge? From what age?