You're very welcome, Ming.
IF the target is a SDS free result:
If you get the first fbx low poly export, merge it in a new project file, select all and use the Mesh> Subdivide. Done.
Yes, the core part is to avoid the SDS during the first part.
Why? Place a cube into an SDS; it gets smaller.
So, the points of the PoseMorph memory keep the position in place, but not so much the PoseMorph "shapes"; the difference is in the pose.
With the first export, all Blend-shapes, including the Base-shape, are untouched by the SDS.
At least, that is my current idea about it.
All the best