To write to everyone send your mail to:
ATTN: Weezer Karl Koch P.O. Box #733 Derby, NY 14047
Now if you want to send it to a specific member (i.e. Rivers) then pay attention. You have to add ATTN: then the persons name. Brian Bell is one funky dude, say I wanted to write him. I would send it to:
ATTN: Brian Bell Karl Koch [ATTN: Brian Bell] P.O. Box #733 Derby, NY 14047
Have fun but seriously, what kind of fan are you if you didn't find that? A bad one, that's what.