Are you sure about that 1 input oject at a time, Penguin? I haven’t tested it in UE4 yet, but I am pretty sure that serveral objects can get input form one controller unless you “consume” the input event in an object.
Anyways, to topic: You should just handle the input information in the object that spawns the projectiles and then pass the values via an init function after spawning them.
In the Projectile you then put the code you have in BeginPlay to the Init-function and you are done.
I usally write Init functions for my dynamically spawned Blueprints, so I can just init them after spawning with the given parameters.
So again:
- Handle the input in the class that spawns the projectile
- Spawn the projectile
- pass the stored values via an init function to the spawned projectile
- handle activating/deactivating of particles in the Init function