Creating a Prefab from an object and I want to add the mesh as a child of that?

I am creating a prefab from a Gameobject that has a procedural mesh, I can create the Prefab and also add the mesh as an asset to the database so it works just fine, and I can add the prefab back into the scene. The only issue I have is the mesh asset is not a child of the object prefab, how do I make it s. I create the prefab using:

Code (CSharp):

1. GameObject prefab = PrefabUtility.SaveAsPrefabAsset(newobj, "Assets/Prefabs/" + newobj.name + ".prefab");
2.  

And the mesh is saved:

Code (CSharp):

1. meshpath = AssetDatabase.GenerateUniqueAssetPath(meshpath);
2. AssetDatabase.CreateAsset(mesh, meshpath);
3. AssetDatabase.SaveAssets();
4. AssetDatabase.Refresh();

So how do I add the mesh as an asset but also so it is in the Object prefab?