RhinoInside NX Problem

Hi, I am coding for RhinoInside NX, there is a NX Body Parameter Component, when i select a NX body. And it converted to a Grasshopper Brep. This works fine now. But when i delete the NX object, i don’t know how to write the code to make it behave just like I delete the rhino object. NX DON’T provide a callback to response for such operation, I am using a Timer to detect if a object is deleted, but it does’t work, when i delete the NX object, and set the coorespond object to null, but the grasshopper brep still exist. Should i call the ExpireSolution method? When?

Is there some tutorial or guide that talk about the GH_Param Class and its member methods?