If you do a search on "goat's milk", you'll find all kinds of threads on the subject.
Some people do a 50% milk, mixing the lye with the water, then, I believe, adding the milk at trace.
I do 100% goat's milk, as I have my own goats, and more milk than I know what to do with! So, I measure out the amount I need, and freeze it solid ahead of time (I fill up a few containers and just leave them in the freezer). When I'm ready to make soap, I take the frozen milk out first, and put it in my lye container (a pyrex pot) to let it soften a little bit. Then I measure out my other ingredients and melt my oils and butters, and put them aside to cool. I measure out my lye, then slowly pour it onto the frozen milk, a little bit at a time. As the top of the milk melts, I scrape it off and keep stirring that, while adding a bit more lye. Eventually, I have a hollow chunk of milk ice, floating in milk/lye, that I can break up (carefully, so it doesn't splash!). I keep stirring it while it melts - the milk turns a pale shade of yellow - until it gets up to the temperature, or close to it, of the oils - around 85 -90 F. I had been putting the pot into a sink full of cold water and ice, but found it was staying
too cold. Once the two are reasonably close in temperature, I mix them together and stickblend to trace.
Hope that helps. 8)
eta: that's frozen MILK, not
soap :shock: