My bad, I sent a wrong answer.
If you need only the mannequins, without control rig and animations, the following will work:
Find the materials and materials instances and migrate them first. You find the materials opening the skeletal mesh editor, asset details, material slots. That will migrate everything associated, material functions, textures, etc. Then export the meshes to your drive and reimport the first mesh into your project. Assign the material instances. Import the additional meshes using the first skeleton.
If you need control rig and animations, first, make sure to enable control rig plugin in the target project. Close it and select the mesh, migrate, uncheck everything outside the folder “Game”. Inside this folder, uncheck everything outside Characters. That should work. Let me know if that helps.