Use the Grouping Tool to select the Body Part, e.g., "rThigh" ...
Then "Assign Material" >>> "kneepad"

Then select the other Body Part, e.g., "rShin" ...
And ...  "Assign Material" >>> "kneepad"

cheers,
dr geep
;=]

Remember ... "With Poser, all things are possible, and poseable!"

cheers,

dr geep ... :o]

edited 10/5/2019