using power you can add it directly to your oils
I did this the first time I made a soap using powdered goats milk. The resulting soap had some white dots/blobs in it. I stick blended the powder really well into the oils (maybe not enough, idk). I figured the white dots in the soap were from the lye water reacting with the oil from the powdered goats milk. I've since been premixing the powder in water and I've had better results. I did read on this forum that many people add the powder to the oils before the lye water is added with perfect results. That didn't work as well for me.
I actually see people not premixing all kinds of things like TiO2, micas, etc and their soap looks great. I tried not premixing that stuff and I got worse results, so for me everything is premixed.