I would let the soap in the skate mold set until it was solid enough to transfer,( time depends on the temp of your poured soap and the depth of the mold). After placing the M&P skates in the bottom of the silicone bar molds, spray with isopropyl alcohol. Pour just enough melted soap to come up a little way on the skates, let it set until it is fairly set on top. This will anchor the embeds. Spray this layer with alcohol. Pour another thin layer over the top and spray with alcohol. Let that set until it forms a skim on top, spray with isopropyl alcohol and pour the rest of the of the melted soap. If you have bubbles or foam on top, spray again with alcohol.