It is a defined class. Running a reasoner would infer it at its proper position in the hierarchy. I know that there was a request earlier this morning on the IAO list for that to be supported by BioPortal; is that an option? Alternatively, I'll update this version to be the inferred one.
ps: is there a way to get automatic notification, maybe via email, when someone leaves a note on your project? I had missed your comment.