For many characters the eyebrows are part of the skin texture of the face; this is unrelated to whether it is a CC3 or CC3+ character. So you did not make a bad purchase that you should feel tragic about.

In CC3, you can convert a CC3 to a CC3+ character, this will not change the texture, but it will make the newer features available.

The presence of the eyebrows as part of the face texture does indeed pose an issue if you want to add eyebrows via make-up or as hair item. I usually adjust the shape so that the original eyebrows are covered. Another option is to edit the eyebrows out of the face texture, but that is not so straightforward.

I mostly create characters using Headshot, in which case it's easy to edit the eyebrows in the original face texture.

There may be better solutions, but I can't think of any off-hand.

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I was half asleep when I submitted this around 3 am. So, if something doesn't make sense or you need some clarification let me know.

Ok, so the key to this is a range mask that you get with SkinGen Premium. 

Start with the default CC3+ Avatar > Activate the SkinGen Editor > Navigate to the Makeup Tab

Right-click on the Eyebrow layer > Hover over Merge Down > Click Current Material

You'll then get a popup asking you what texture size you want to bake into the base texture. Here I choose the 2K texture and click ok.



Click OK on the second popup.



You'll notice the Eyebrow layer has disappeared from the Makeup Editor and has now been baked into the base texture.



Using the Makeup & SFX pack

(If you don't have this pack scroll down to Using the Eyebrow Tool)

Now let's add the Curved Sparse eyebrows from the Makeup & SFX pack. This can be done by either double-clicking on the icon or by clicking and dragging it onto the avatar.



You'll now have a new Eyebrow layer in the Makeup Editor. Right-click on one of the hair textures and select Find Image File.



Windows File Explorer will open up to the texture location.

You'll then need to navigate to the following location:

...\Reallusion\Template\Character Creator 3 Template\Texture\SkinTextures\MakeUp\4_Range\SkinTool



On the Eyebrow layer scroll down to the Replace Section > Check the Active Box > Click and drag the EyebrowTool_ReplaceMask into the Range slot.






Using the Eyebrow Tool
(If you followed the steps above, you can skip this)

Replace the Texture Patterns with your eyebrow texture and then delete or replace the normal maps.

The rest applies to both of the above methods

On your eyebrow layer scroll down to the Replace section and change the Material settings as shown below:



Next click the color swatch > In the window that opens use the Pick Screen Color tool and match the eyebrow skin color as closely as you can to the surrounding skin. I used #c69b85.



Scroll down to the Noise section and check enable. Then change the Color settings as shown below:



Before:



After:

Just keep tweaking the settings until you get a result you're happy with.

If you don't want eyebrows simply delete the pattern textures, but only after you've finished adjusting the Replace and Noise settings as they will be grayed out as soon as you delete the pattern textures.