Hello @FilmDaft, I can help you with that!
First thing you need to do is to set up a Leader Pose in your character BP, if you haven’t already. You can do it by following this guide: Working with Modular Characters in Unreal Engine | Unreal Engine 5.5 Documentation | Epic Developer Community
One way to achieve you want is to create an Animation Blueprint that will layer the body and face animation. If you’re not familiar with that, you can read this documentation page so you better understand how it works: Using Layered Animations in Unreal Engine | Unreal Engine 5.5 Documentation | Epic Developer Community
You can create a new slot for the face and connect it to the Layered Blend per Bone node that will have a layer for the face bones. You can either use the Branch Filter if you have a root bone for the face or you can create a Blend Mask for all the face bones: Blend Masks and Blend Profiles in Unreal Engine | Unreal Engine 5.5 Documentation | Epic Developer Community
After doing that, you need to apply the ABP to your head mesh in sequencer. You can do that by either selecting the Head, going to the details panel and setting Animation Mode to Use Animation Blueprint and set your newly created ABP as the Anim Class.
You can also do that in Sequencer by clicking the + next to the skeletal mesh component and selecting those same options:
Finally, if you have an animation track with your baked animation, you will be able to right-click the animation track, and under Properties > Slot, you can type the slot you created for the layer (in this case, FaceSlot). If you’re not going to use Slots for anything else, you should be able to use the DefaultSlot in the ABP and you can skip this last step, as it’ll automatically be set in the properties.
I hope that helps and that I understood your question correctly. Please let me know if that works for you or if you have any other questions!