HP-UX patch structure
Hunting patches for HP-UX is not a simple task. Patch IDs are different for newer versions of the same patch, meaning that a newer version of a patch will have no meaningful connection to the previous version of that patch.
I have discovered that the best option is to track the patch is by finding out what is the subsystem which has been fixed by its predecessor, and searching for this subsystem in this HP-UX patch search engine or in this entire list here.
Good luck.