What can I use instead of powdered milk to turn dark chocolate into milk chocolate?
Milk chocolate is made with powdered milk; adding a liquid will make it break or it'll be unable to set. If you add something with enough fat to keep it from breaking, like coconut milk, you'll end up with a delicious chocolate ganache, but it won't set like a chocolate bar. I would instead look for a vegan milk chocolate; some companies are making them with coconut milk solids. You may have to order them online.