Weight painting for new mesh

[Vwings]

I added a new mesh made in blender to my mmd model by clicking "Atach meshes to model".But there are none vertex groups created for this new object, and I can't paint weight on this mesh.I found a solution: click "Join Meshes" and then "Separate By Materials", and vertex groups were added on my new mesh, but the Subdivison modifier was also applied. Is there a better way to paint weight for new mesh?

[powroupi]

Select your mesh object -> Shift select armature object -> [Ctrl+p] parent [With Empty Groups] or [With Automatic Weights]. (Inside 3D viewport menu, [Object]->[Parent]->[With Empty Groups] or [With Automatic Weights])

[Vwings]

Select your mesh object -> Shift select armature object -> [Ctrl+p] parent [With Empty Groups] or [With Automatic Weights]. (Inside 3D viewport menu, [Object]->[Parent]->[With Empty Groups] or [With Automatic Weights])

Thanks