HD_Tools_Make_Multires - Diffeomorphic/import_daz GitHub Wiki
Make Multires

Here we have imported a HD character into Blender. There are two meshes, the original one at base resolution, and a HD mesh at the resolution specified in the DAZ Studio.
If the file was imported with the default settings, the importer adds a Multires modifier and tries to rebuild subdivisions (from Blender 2.92 where this feature was introduced). the multires mesh has the same vertex numbers as the base mesh, so vertex groups can be copied from the base mesh.

If multires is disabled in the global settings, the HD mesh has no vertex groups and thus cannot be posed. But we can add multires and copy vertex groups from the base mesh afterwards.

With the HD mesh selected and the base mesh active, press Make Multires. The HD mesh acquires a multires modifier. The vertex count is the same as the base mesh, and the vertex groups are copied to the HD mesh.