Apologies for the very late response! With the removal of classic SL3D in R2025a, we would recommend using the Simulation 3D visualization that uses Unreal Engine instead of the 3D world editor.
You can easily set the Parent of an object in this environment, and specify its translation relative to the parent so that two meshes can appear to be joined together. We also have a Joint construct that you can use to achieve this.
If you are unable to try out Simulation 3D, let me know!
