Cant load in meshes

Hi. We need to see the blend and package files. Most likely polycount is too high.
Also, joining yours with the original is not the right way of doing things, weights arent assigned this way

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There's something wrong with the .blend file. I tried opening and appending in Blender 3.3 and Blender crashed. Then I tried opening the blend in Blender 2.78 and the mesh appeared empty. When I tried appending in Blender 2.78 Blender crashed. Go back to a previous save if you have one. Or you could just as easily use an .obj file, if that's all you have. You'd just need to open the EA mesh, append your mesh—you don't even need to append the floor shadow mesh as the EA mesh already has one—position your mesh where you need it, assign your mesh to transformBone, make sure your cut numbers are assigned correctly, resize the floor shadow mesh if needed, delete the EA mesh, then save. Just a simple mesh swap. This tutorial is old and it's for converting a TS2 item to TS4 but the concept is the same. The only thing that's different for you is that you're not exporting meshes and textures from SimPE.

Anyway, your blend file is FUBAR. You'll need to use a different file.

Oh, and if you're making a plant your mesh might need to utilize alpha transparency. If that's the case you'll need to clone something with two mesh groups because one of the mesh groups will need to be assigned to the Phong shader. In that case, clone something that has glass. The glass part will already be assigned to the correct shader. You just need to make sure that the parts of your mesh that need transparency (e.g. if the leaves are flat planes with a leaf texture painted on and parts of the flat plane to be invisible in game) are given the same cut number as the glass part of the EA mesh. I hope all that makes sense. I don't know what you're making so I can't say for sure if you can use the books you cloned or if you need to clone a mesh with glass parts.