Can a relation have non-existent relata, asks Bill Vallicella. Surely not. For we have to ask what kind of relation it is – one-termed, two-termed, three-termed, or whatever. Let’s suppose it is two-termed, i.e. it has two relata. If one of those were destroyed, i.e. made non-existent, it would only have one relatum. If both destroyed, none. Frege said it well: that the number zero represents the denial of existence. If the number of Fs is zero, then there are no Fs: no Fs exist.
Thus if a relation has two relata, it has two existing relata.