I recently purchased CC3, and iClone7 for various projects.
One of those projects involves painting human multiple figures and I was eager to apply and use the tattoos/decals feature.
It is very clearly advertised  on the website under new features of CC3 (Morph - Outfit > Suntan & Tattoo.) https://www.reallusion.com/character-creator/morph-outfit.html
There is no *asterisk, as there is with the "Aging" feature saying that Essential Morph & Skin content add-on is required.
After being unable to locate the feature for several weeks, I started searching the forums, and the FAQ and read how the feature was only available with the Essential Morph & Skin add-on pack.
Even though I feel like I've been swindled, and this is a classic case of misrepresentation, I still broke down and purchased the Essential Morph & Skin add-on pack. 
Well I still can't find out how to put tattoos on my characters. The manual covers adding decals to cloth items, but nothing about the figures, and the same options with items are not available on characters.
I've been having to load the skin textures one by one into my paint/photo editor and then paint them manually, and reapply them, which isn't efficient, and I need to re-do it whenever I change characters.
Why can't i apply a decal/tattoo to a body part?? What am I missing please.