When using a lot of speedtree objects in a scene, it soon becomes impossible to keep track of speedtre objects (ex. switching between visible/not visible (to save resources when doing animations), keep overview of which objects is placed in a certain location in a scene, etc...). The ablity to attach speedtrees to another speedtre object (or maybe a new speedtree dummy container object) to create a hierarki would be a nice addition.

It should also be possible to save a "group" of trees, for reuse.