I have created several collections of my own shader materials for clothes I modelled for the La Femme and L'Homme figures. I find I need to adjust the shader trees (I made both Poser Root Surface and Cycles Root Surface versions for the same input textile graphic). Is there a way to change the shader trees without having to actually load the shaders onto the clothing ?

The alternative for me is to release the setsand tell users (if anyone gets around to actually using them), that they have to make the modifications themselves, and how to do it.

Argh - post header misspelled trees as tress !

Hea, we all do that ... we understand! I'm not sure what you are asking, but I'm sure that someone will come in who does.

I would suggest loading the material pose files onto a prop. Poser will ask whether to create materials if they do not exist. You can then edit the materials on the prop, though it won't be visible except as a preview in the Material Room, as the prop won't have any facet groups associated with the dress materials.

If you pick a prop like the box, which only has a Preview material (everything always has a preview material, as Poser will create it even if the obj file doesn't refer to it), there won't be any extraneous material names, so you can save the modified shader trees on the prop back to the library.

Poser is by far the best tool for editing material pose files. It can be done directly with a text editor (provided it can automatically handle compressed files, like Notepad++ on Windows or BBEdit on macOS), but you won't have any of the GUI features like dragging nodes around to adjust their position coordinates, and if you make a typo, you can break the file completely.

if you know the content of the lines you need to change, you can write a script to do an edit in place using string.replace("this","that) or you can use poser file editor or a similar util ( I believe PhilC also made something similar )

Poser File Editor is one of the best one. For a vendor it's more or less a must have tool.

PFE does not run on MacOS without a Windows emulator.

PhilC's is called PZ3editor and is available both here and on his site (it's one of the few things still there).