Hey newimaging,
Yes, the method of running animation tracks through different slots and combining them in an animation blueprint works as of 4.13.
Essentially you import the facial animations as additive, then create two slots (Body and Face). In the AnimBP, you plug the two slots into an Apply Additive node. After this is applied to the skeletal mesh in your level, you can play animation tracks through those slots. It essentially plays them both at once.
The other method is to avoid additive and do “Layered blend per bone”, like below:
On a side note, we will have the ability to blend animations on the timeline in future releases, but to play multiple animations on different parts of a , you’ll need to use slots.