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I used to work at a charity place, we sorted out the donations and such.
I mean for where I worked, if something came with a little bag of stuff taped to it, we'd keep them together. People would just chuck loose lego, rc cars and all that, but nothing was together so we had to toss it instead of wasting time putting it together ourselves.
I can't speak for all of them but if you tape a little bag of pieces to whatever, they should try and keep them together.
Failing that, could just do the same thing but in a box so everything will stay together even when being jostled and sorted.