Need help to combine face and body's motion data inot UE

Hi everyone.
When I read the topic about FaceAR Sample in there: Face AR Sample in Unreal Engine | Unreal Engine 5.2 Documentation.

I am have a model with full skeleton of face and body.

I want to take different types of mocap data and assign them to the same my model within UE4 4.20.

I will transfer mocap data of body by Optitrack system and transfer mocap data of face by iPhone X.

I want to show the body and face can motion in real-time in my model but I am feeling on down the road. I am stuck at there !!!
I need your advice for my problems:

  1. Do we need separate face / body (which its skeleton) animation imports (FBX) in UE4 workflow? Or just import a model which has full skeleton and face animation? What is most importand we need to know when do this?

  2. I already transfer successfully the motion of body into UE4. This is topic for do this:Unreal Engine Plugin | Streaming Skeletons on Vimeo
    But with the motion of face which use Live Link plugins, I get many misunderstand to do it.

Especial, how to create correct face animation/skeleton? What is the main Blueprint which we can focus for tracking face via iPhone X?

So can you give me more useful information to transfer motion from iPhone X to UE4 .

Thank you so much.