I'm running into this as well. The Creo Manikins have three serious problems that I'd like to fix...
1.) The legs and arms are not there; all you have is some baggy pants and a baggy shirt. These can entirely cover up equipment that should fit the sizes of people the manikin is representing.
2.) While there are percentile manikins, the 7 'standard' humans that the US government bases things on are not there. In particular, the wide shoulder male is not even close to being represented by any of the manikins.
3.) The Natick manikins are based on the old study from the 1970's that has been replaced by the 2012 study...so they are essentially junk.
So...I go to edit one of the parts (the left calf). Creo 4 refuses to open it because it is a Manikin component. I open the part in Creo 3. I insert the accurate version of the left calf, hide the surface that was representing the left calf (because it can't be deleted), and save. I reopen the manikin in Creo 4. At this point the only thing changed is a hidden surface and an added body in a part. It opens with the new left calf. Then I try to apply a posture and Creo refuses because "Could not perform the operation because the manikin is not complete". My company has multiple different manikin licenses but none of them let me edit a component. None of them let me edit a manikin directly. I can hide/show things, I can make changes to layers, I can even add additional parts...but I can't modify the parts that come with it. As for that additional parts thing, it's not really ideal because whenever you change posture you need to do a regen...and in our assemblies that can take an hour easy. The parts built into the manikin don't have that issue.
From everything I can tell, PTC locked down the manikins. For some reason they don't want anyone making changes to them even if they bought every Manikin license offered. This is only compounded by the fact that PTC won't make good (or at least up to date) manikins. I've been fighting with this for the last week...I have all the licenses offered, I even have 3 different versions of Creo installed so I can get around some of the locks. Yet still, even if I get around the locks on part modification, the program just refuses to move the manikin with those modified parts.
It's starting to feel like the Creo way...it seems like every new feature is either something that everyone else had 10 years ago or it's something that looks really useful until you actually buy it and find out that PTC has blocked you from using it in a useful way for no reason. I'm about ready to just make manikins using simp-reps and consider the whole manikin add-on to be snake oil.
