Hi. Your blend file contains one meshgroup while the item you started the package from is made of multiple. Upon import, only one meshgroup is replaced while others stay.
Unrelated issues:
- your garment comes with shoes while the reference didnt, so the shoes received data from the skirt instead of feet. It would b best to make shoes as a separate item;
- transfer all data with Nearest face interpolated;
- After transferring weights, use Limit total, otherwise some areas of the garment will spike;
- you seem to be jumping between versions of blender, dont do it;
- a dress should be vertex painted with two colors, you should transfer them;
- do not join the body with the garment until the latter receives all data, otherwise the data of the body will be overwritten.
Do the following:
- delete all vertex groups (Vertex groups specials - Delete all groups), uv_1 and both color attributes from the dress;
- in the uv editor enable sync, hover over uvs of the body, press L, select all of them like this;
- in 3d view press Delete, choose Faces;
- select uvs of the shoes, in 3d view press P, choose Selection to separate, rename the separated meshgroup to Shoes,
hide them;
- clone
yfBody_DressMaxi, export the blend, append in the scene, join all parts into one, rename to Reference;
- transfer weights, uv_1 and vertex paint from the reference to your garment, then Limit total;
How to make an item move and morph by transferring weights, uv_1 and vertex paint
Transfer weights, uv_1 and vertex paint with Data transfer. The result may not always be perfect, but it is best to solve problems as they come:
- Unhide the reference. It must be visible* ( eye icon ) and selectable* ( cursor icon );
- Select your hair;
- In Modifiers tab add Data transfer modifier;
- Choose Reference as Source object;
- Enable Vertex data and expand it;
- Enable Vertex groups*;
- In Mapping choose Nearest face interpolated;
- Enable and expand Face corner data;
- Enable Colors*;
- Shift*-click to enable UVs as well;
- In Mapping choose Nearest face interpolated;
- Expand UVs, choose uv_1 in Layer selection ( don't forget, otherwise uv_0 will be overwritten as well);
- Click on Generate data layers*;
- Apply the modifier;
- In Data tab expand UV maps. Double-click on UVmap, rename it to uv_0;
- If uv_1 appeared, it most likely transferred successfully;
- Expand Color attributes. If you see color0, it transferred;
- Expand Vertex groups. If you see names of vertex groups, they most likely transferred successfully. However, there is one ( or two ) more thing(s) you need to do;
- If you're using Blender 2.76 - 2.79, 3.6.1, switch to Edit mode, select everything with A, Mesh - Weights - Clean with Subset set to All groups to fix the result of a bug that exists in these versions;
- Regardless of your version of Blender, in Edit mode, with everything still selected, do Mesh - Weights - Limit total.
* Data will not transfer if you will forget to do these steps!!! | 
|
- select the reference, in Edit mode select everything with A, Mesh - Merge - By distance;
- enable X-ray, select all areas of the body covered by clothing, delete;
- split sharp edges;
- join the reference with the garment, give it cut 0, save this blend;
- filter the catalog by Clothing body and one meshgroup, clone a dress, import your blend there, make other maps blank, test in-game, do the rest.
About shoes:
- open the blend, File - Save as, name this blend shoes;
- delete your dress, unhide shoes;
- expand the rig, make feet visible and selectable, select them, in 3d view press Shift D, then Esc to duplicate;
- select feet.001, in the uv editor select soles, select them, delete in 3d view;
- select your shoes, transfer weights, uv_1 and vertex paint from feet.001;
- select feet.001, merge by distance;
-
in this order: select feet.001, then your shoes, join, give cut 0. Clone shoes, import;
