Metahuman Animator is a great way to record facial performances. Often people record the body motion at the same time, but what if that was not possible? This tutorial goes over the steps to layer your face and head motion smoothly on top of existing body motion.
https://dev.epicgames.com/community/learning/tutorials/epLR/unreal-engine-how-to-merge-a-metahuman-animator-head-onto-a-body-using-a-custom-anim-blueprint