FYI, that's not actually possible to do with AO3 exchange matching when you're also trying to match on medium (art or fic.) You have to either choose the Character field (thus requiring ships be nominated as something like Group: Character A/Character B) or the Relationship field (this requiring characters be nominated as something like Character A & None) for all characters and ships, and then use the spare slot for art/fic. Most exchanges pick the relationship field for characters/ships, because relationship tags tend to be longer in general and AO3 has a hard 100-character limit on all tags, so having to add "group" creates more problems.