Maybe useful to someone.
I use matyalatte's psk plugin for UE, plays nice with Maya/3ds max as well.
If you are exporting to unreal the blend shapes/morph targets should be applied before bind skin.
Import morphs from spiritovod's export morphed models Umodel build (legacy Desktop version builds if exporting out fbx for UE)
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Import morphmesh/delete Armature, Import next morphmesh/delete Armature, ect so only geo/morph meshes are in scene (no armature/joints).
Rename morphs/geo to whatever they were in umodel.
Export all to single fbx (Blenders fbx exporter).
Import psk/target (The one that got exported along with the morphmesh psk's) in new scene.
Save blender scene.
Export out to fbx (using matyalatte plugin).
Import both fbx to Maya.
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Blender's Shape Key