@Goth
maybe try this dressing tool called AvatarTools by 黒鳥ケモノ工房
https://booth.pm/en/items/1564788

Download the AvatarTools_v2.2.2_BETA.zip
https://booth.pm/downloadables/2491319

AvatarAssembler is what you need.
SkinnedMeshCombiner usually not needed.
And, have good sleep.

i don't know which one is better, need to try.
here is another version maybe newer of AvatarTools
AvatarTools 2.2.3 by Atelier Takec
https://booth.pm/zh-tw/items/3411988
https://booth.pm/downloadables/2532084