I would like to ask a question about vtkassembly. The problem is more complex and is written in the content

When I use vtkassembly for assembly, it is assumed that there are two objects in my space at this time, but these two objects are added in render in the form of actors. Adding an actor to the assembly at this time will result in a new actor being generated and added to the assembly, and the original actor still exists in the space. If I delete the actor in render at this time, I can get an actor existing in the assembly, but its properties have been lost. I can’t get the position of an actor in the world coordinate system through getposition. Please ask me how to get it. If there is a problem with the starting point of this method, If the actor in render cannot be added to the assembly, how can I bind two objects into one and move them at the same time?