Thanks.
I'm starting to wonder if maybe we could suggest that God's knowledge causes things in different ways, perhaps according to how that thing relates to God.
In that case, if we can argue that the past, present, and future relate to God in different ways, then we can say that they have different kinds of existence. This apparently requires God entering into time with (say) the advent of the universe, and that seems unacceptable for other reasons.
Oh well, it would be interesting to explore, not that I have the least idea where to start.