Lucid MP soaps are made with lye so not good for children, You need some knowledge about skin, before you do anything. For children you need very gentle surfacants soap
You say you will be trying it, everyone has a different skin and more than one person needs to test your soaps for some time, before they can be some suggestion made. The butters you plan to use will not help with lathering, Keep them for different products
Find Fisher on internet he gives you a lot of basic soaps. Start with 3 oils, no scent no colour, I was making soap for two years before I put some on sale, a lot of my soaps were not good enough to sale