Rearrange the data hierarchy (and UI) so that behaviors are a soup and behavior sets are assembled piecemeal from the list of existing behaviors. Consider adding a "behavior category" ply to the hierarchy, so that the behavior soup is not unwieldy.
The actual behavior set part of this has been done for a while; I'm going to go ahead and close it and open a new item for behavior categories/hierarchies if that becomes a desirable feature later on.
Rearrange the data hierarchy (and UI) so that behaviors are a soup and behavior sets are assembled piecemeal from the list of existing behaviors. Consider adding a "behavior category" ply to the hierarchy, so that the behavior soup is not unwieldy.