You could compare the amount of water recommended to hydrate the milk to the amount of water in your recipe.
Usually, I just put in about one tablespoon PPO. I mix it with the oils before adding the lye solution & use my stick blender to mix it to make sure there's no clumps.
Hope this helps!
I use liquid Coconut milk and add powdered to make it full milk. I just mix the powdered into enough liquid to dissolve it. I tried adding it right to my oils but still had clumps even with heavy blending. I mix my lye with water.
I use 1 TBS coconut cream powder ppo. I mix it into liquid aloe that I use as a water replacement (the extra water I need for masterbatched lye water 50:50). I SB blend the aloe with coconut into the oils before I add the lye water. I find that it’s good to mix the coconut cream into the liquid aloe about 30 minutes in advance and sometimes I warm it just a bit to ensure that the powder is fully dissolved.