[Haskell-cafe] Dynamic collections of wires with netwire?

I'm using netwire to make a top-down shooter; the player can spawn projectiles by clicking, and projectiles will destroy themselves and whatever they hit on collisions. So the way I'm thinking of this is as a collection of wires, one for each projectile, that I can cast input events to; however, I'm not sure how to deal with the fact that the set of wires is dynamically changing, since you can't do projectileWires <- accum (++) [] -< newProjectiles projectileState <- multicast projectileWires -< () or whatever. Do I have to write the relevant code out by hand using stepWire/stepWireP, or is there a nicer way?