The archive contains multiple .blend files for 2.79 and 2.8 versions.

Creating new model:

• One armature for all models

• Choose the head object prefixed with "head_..." from the outliner list

• You can also apply border to it, choose the next object from the outliner prefixed with "head_sameName_border"

• Choose the body object prefixed with "woman_..." from the outliner list

• You can also apply border to it, choose the next object from the outliner prefixed with "woman_sameName_border"

Importing fbx models:

• In order to join the body and the head correctly you should turn the aplha for one of the materials. Choose the head or the body object, check the materials tab, choose "alpha" material and make it transparent(for Eevee render engine you can use Transparent BSDF shader/surfaceIn Blend Mode choose Alpha Blend and make sure Show Backface is checkedIn Eevee properties tab turn the Screen Space Reflections and make sure Refraction and Half Res Trace is checked).

Changing "alpha" material will apply changes to the head and the body.

• If you want to apply a border mesh to a character, you should show only a backface of that mesh. Choose the border of the head or the body object, check the materials tab, choose "border" material and Use Nodes to apply custom shader as shown on the image(shader is included).