DH and I are updating our will's and other paperwork. I want to go ahead and get a vax exemption (religious) for ds to include with it to hopefully prevent him from being vaxed if something happened to us (my sis would have custody and doesn't vax, but I want something from us in case there is any question of her not doing it). So, what does it take, exactly, to get an exemption? I live in Washington state, and on the back of the immunization form it has a box to check that says you don't want your child to have (and then you list the specific) vaxes and you sign it. Is that it or do I need something more "official"?