If we look closer, Henry would make some further clarifications about the kind of production. The Father produces the Word by the power of intellect; the Trinity of divine persons produces creatures by the power of will; this productive act by will presupposes knowledge about possible creatures (creatures that are metaphysically possible to be created).

So, yes, as JT indicates ‘modal property’ here does not means ‘possible worlds’ or some such Lewis-ian scheme; rather it just means a kind of existence. The kind of existence is a relation, specifically, a causal dependence relation _being produced_. Further, if we compare the property ‘being produced’ of the divine Son and of creatures we find that this is not exactly the same property b/c the Son’s property _being produced_ is _necessarily being produced by an intellectual act_ and creatures’ property _being produced_ is _contingently being produced by an act of will_.
And, as mentioned above, Henry would add further distinctions btwn. the creaturely property _being produced_ and the divine personal property _being produced_ by talking about the identity of the Son/Word with the divine essence, whereas creatures are not strictly identical with the divine essence but only with their divine exemplar. (Perhaps I’ll post later about Henry’s acct. of divine ideas/exemplars.)

(Also, perhaps ‘relational property’ would do the job in this context?)