dynamic objects in ABT

Hello, the last days I read through some of the very interesing threads about ABT''s and Yann''s game. In one of his posts he said he is using a second ABT for dynamic objects. I thought about using something similar in my engine, but I came over a big problem. I cannot split dynamic objects when splitting an ABT node, because this couldn''t be treated together with animation/movement/LOD. Thus I have to find a split plane that doesn''t intersect any of the dynamic objects. But this is not always possible. Let''s take a forrest as example. The trees are all dynamic objects (because of wind, etc.) and they stay close to each other. In most cases their bounding volumes will intersect, because branches in the tree-top will range into other tree-tops. But how can I split the ABT node now. One possible solution would be to store the trees in each node they intersect and flag them as already rendered when traversing a second time. But this leads to the problem where to set the split plane. Another example are huge dynamic objects like a rain particle system. A possible solution here would be to split the particle system into smaller ones. I would love to hear some other opinions on this topic. Ciao, Thorris.