Prefab Mesh=> Create

    public static PrefabMesh Create_PrefabMesh( int branchKey, GameObject prefabMeshGO)

Example:

//Create a spline plus game object at Vector3.zero
var sPData = SplinePlusAPI.CreateSplinePlus(new Vector3(0,0,0));

//Add a deformed mesh component to the spline plus game object
var deformedMesh = sPData.Add_DeformMesh();

//Create a new prefab Mesh for the branch with key 3  
  deformedMesh.Create_PrefabMesh(3,prefabMeshGO)

//Update procedural mesh generated on all the branches
deformedMesh.Update_Branches(true, true);