c4dmdn, cyanide, ninkul, THANK YOU for your replies! that completely answers my question. appreciate it!
i just tried what had been suggested when attempting to place more than 1 game on a memory stick: no need for using the UMD_DATA.BIN file and overwriting any prx files that already exist. after doing so (i only chose to overwrite prx files when the one to be overwritten was dated older), the one game that had been working (nba) then no longer had sound, but otherwise ran fine. would anybody have any idea why this occured? thank you very much