Changelog v2: I added two more morphs, in this case, responsible for an extra boob below the breasts. I also added the two example decals for the nipples, just in case. I actually started with the morph for the extra boob located in the middle of the breasts, but it's been kind of tricky to do something decent without breaking the mesh on the breasts, so this one might take a little longer for me to sort out the issues.

Another important detail. To create the morph without increasing the number of vertices in the base model, I had to manipulate and stretch some faces of the mesh a bit, which caused a bit of distortion. It also made it very difficult to create the nipple directly on the mesh, so I couldn't add it to this version of the morph. This also affects the textures and clothes that are in contact with that part of the mesh. So, if you want to add new nipple decals, I recommend you to follow the size and proportion of the decal included in the pack.

The VAR Extra Boob contains 4 morphs and 4 decals:

...\Morphs\female\CasuaLooks\ExtraBoob\ExtraBoob_center_down_1.vmb

...\Morphs\female\CasuaLooks\ExtraBoob\ExtraBoob_center_down_1.vmi

...\Morphs\female\CasuaLooks\ExtraBoob\ExtraBoob_center_down_2.vmb

...\Morphs\female\CasuaLooks\ExtraBoob\ExtraBoob_center_down_2.vmi

...\Morphs\female\CasuaLooks\ExtraBoob\ExtraBoob_center_top_1.vmb

...\Morphs\female\CasuaLooks\ExtraBoob\ExtraBoob_center_top_1.vmi

...\Morphs\female\CasuaLooks\ExtraBoob\ExtraBoob_center_top_2.vmb

...\Morphs\female\CasuaLooks\ExtraBoob\ExtraBoob_center_top_2.vmi

...\Textures\CasuaLooks\ExtraBoob\torsoDecal_ExtraBoob_center_down_1.png

...\Textures\CasuaLooks\ExtraBoob\torsoDecal_ExtraBoob_center_down_2.png

...\Textures\CasuaLooks\ExtraBoob\torsoDecal_ExtraBoob_center_top_1.png

...\Textures\CasuaLooks\ExtraBoob\torsoDecal_ExtraBoob_center_top_2.png

The VAR Extra Boob N contains 4 morphs, 4 decals and 4 normal maps:

... < all files from Extra Boob N >

...\Textures\CasuaLooks\ExtraBoob\torsoDecal_ExtraBoob_center_down_1_Normal.png

...\Textures\CasuaLooks\ExtraBoob\torsoDecal_ExtraBoob_center_down_2_Normal.png

...\Textures\CasuaLooks\ExtraBoob\torsoDecal_ExtraBoob_center_top_1_Normal.png

...\Textures\CasuaLooks\ExtraBoob\torsoDecal_ExtraBoob_center_top_2_Normal.png

I would recommend you choose only one of the two VARs to avoid file duplication. If you are interested in testing the normal map, choose the second file, if not, choose the first file to save some space.

For those interested: Board of Suggestions