I'm going to have to guess here since the 1st post was edited...
Yes, you can make dummy packages to fix "package not found" or "(something) not found in package" errors. Be it a blank texture, sound, whatever, the engine doesn't care as long as it exists. If you suddenly get this error from a map you've been working on just make a dummy package w/ temp content imported (ex: silent sounds). Use this to get the map loaded and then replace the offending actor/properties in the map w/ valid ones.