I've wondered the same thing! So far never had problems with embeds, but I don't use them often. I think as long as there's soap all around it should be fine, but if you're worried you could try to force gel. I think I've read about someone who 'welded' pieces of soap together by pressure and heating. If that works, I'm expecting a gel phase should be enough to make an embed surrounded by fresh soap stick for sure. (I'm sorry can't find any info anymore on the soap welding technique.. anyone know what I'm talking about and where to find it? I should really bookmark more..)
I tested the welding technique with soap that was several months old. Grace (From Grace to You) explains the technique in her ebook and I wanted to try it out. I used that soap while traveling the past month or two and the welds held with no hint of pending separation. The post I did about this little test is
here. Grace's ebook is
here. If you look at the picture in my linked post, you will see that the soap was 9 months old when I cut it and welded it, so the age didn't matter. For more information about Grace's welding technique, see chapter 10 in her ebook. On page 67, the photo shows a heart embed in the middle of the soap. If you click on the image of the soap, it takes you to a video of her making that soap. The welded soap I made was more along the lines of the soap on page 73 in chapter 10. But the Message soap has embeds, so I thought you might find it interesting.
In any case, I wouldn't worry about the embeds sticking in CP soap as long as you gel the end product.
I have purchased MP soap that was made in layers, that did fall apart with use. So I don't trust MP to stick together well with a simple alcohol spray. But my experience with CP is, that with the soap & water as the glue + heat, is that is lasts extremely well and the soap does not fall apart.
I know some people mix and match, using MP embeds in CP soap and vise-versa. I have not tried that myself, and have no personal experience how they withstand the test of use over the life of the soap.
Edit: I should clarify that although the soap was 9 months old, I had wrapped it entirely in plastic wrap to prevent it from completely drying out. My plan in doing that was to come back to it later to use it to create an intaglio soap, with it as the center and pouring the surface with new soap. Therefore, when I did the soap welding experiment, it was not with soap that had sat through a normal cure with air flow the entire 9 months.