Am I misremembering in thinking someone had devised a way to do this? a script, perhaps?

Cage was working on hair room scripts a year or two ago. I think he had something. Try a search in the forum here.

I never delved into copying, duplicating, or mirroring hair groups, anything like that.  Part of the problem (as I would see it, anyway) with approaching that in a Python script would be that Python gives us limited access to Poser groups.  If we're talking about duplicating the shaping or styling of guide hairs, a lack of symmetry in the hair group or the geometry of the hair prop would be another problem.  If the groups or geometry don't have symmetry, then you would basically have to tackle the problem of comparing dissimilar meshes to be able to come as close as possible to symmetrical shape transfer.

It would be useful if Poser Python gave us access to the group, morph, and weight map symmetry tools added to recent versions of Poser.  Actually, it would be useful if PPy had access to bunches of recent Poser additions.  Give me low-level access to the fast mesh comparisons Poser can do these days, and I will certainly start tinkering!  :lol:  Poser now has built-in features which are hard to approach in pure Python, largely for speed reasons.  Ooh, I wish they would expand Python.

It's frustrating that there's no copy/duplicate function built in for props. After all, the function is there for figures. And obviously Poser has all the data stored somewhere, or it wouldn't be able to display and render the prop at all.

The hair settings script I posted (the thread was bumped recently) might get you partway there, if those settings cover the level on which you want to copy the hair groups.

I guess we could be talking about three separate things, with dynamic hair.  The hair prop would have a hair group applied, which has its own geometry grouping and its own settings.  Then there is the guide hair styling, both using Hair Style tool or the styling controls.  The script I posted covers the styling controls.  My musing about Poser Python limitations, above, relate more to the hair group and or the Hair Style results.  I suppose the whole system could be... a bit more straightforward, somehow.  :lol:

I basically want to duplicate the whole thing and keep it parented to the skullcap prop.

Why? Because the two hair group props can act as hair layers, giving additional depth to the hair. After duplication, the second layer can be repositioned slightly higher on the Y axis and given a lighter colour, slightly lengthened, whatever.

This is much easier than creating an upper and lower layer manually, which I have found tricky—far too easy to get them intersecting each other in unfortunate and unrealistic ways.

I guess the workaround would be to save the skullcap with hair props, then load it and reparent the hair props to all be on one skullcap.... I assume that would work.

Hm. That idea didn't seem to really work. At least, when I loaded the resulting hair prop back in, things appear okay until I get to the hair room, at which time the reparented props don't have actual hair groups, even though they do appear in the material and pose rooms.

I suppose one could simply keep both full hair props and work with that.

So you're just dealing with the actual hair prop and its group, nothing to do with the guide hairs?

This might be easiest if you set up both props separately, then merge them by editing the files together in a Poser file editor.  Poser seems to be... quirky about handling hair groups.  When I duplicate a prop with a hair group, it isn't copied.  Geometry groups are copied with duplication, but not hair groups.  A Python script can convert a geometry group to a hair group, but can't fully duplicate an actor without resorting to file I/O operations of one kind or another.  If I were trying to approach the project you're tackling (assuming I'm understanding you correctly), I think I would work with editing Poser files.

Well. I'm wanting to copy everything, including guide hairs, styling etc.