That may work but what actual use would it be? You would be plugging one of a million holes. A general solution is needed.

Not necessarily. The problem may be as simple as the fact that LLMs do not see "dog legs" as objects independent of the dogs they're attached to.

The systems already absorb much more complex hierarchical relationships during training, just not that particular hierarchy. The notion that everything is made up of smaller components is among the most primitive in human philosophy, and is certainly generalizable by LLMs. It just may not be sufficiently motivated by the current pretraining and RL regimens.