Yea - you'd need to keep store the path to where you found the group in the first place.

I just wanted to put the vertex in the selection for drawing considerations, but I'll do it in an other way. For the moment, I'm trying to found a memory leak when I try to send my mouse coordinates to a Webdialog for displaying it using the InputPoint class and the position method. It takes me a lot of memory and then makes sketchup very slow.