Let's say I am all knowing of what would happen,
I find this desiring more info. I understand what follows is an attempt at that but the 'what' here leaves a lot to be desired. Even in the very very very shortsighted example.
and I have to throw away a pop bottle, although I know there is a wasp's nest in there, and the next person who will come will be strolling her 2 month old baby boy, giggling at the wind. She will need to throw a candy wrapper away, but once they open it the baby will get stung and die, being allergic to beestings, and the woman will be trying to escape the swarm.
Am I held responsible for the child's death?
No.
Primarily because there is no death. Not in reality.
From this all important point, the other aspects of argument pertinent to what you are getting at (I think) is a) you didn't have to throw away pop bottle, b) you apparently didn't know effects it would have on (all) others and c) mom didn't need to throw a candy wrapper away
Or was it the freewill of the mother who had opened it up with her child there?
Has next to nothing to do with free will as you have it set up. You are referring to (illusion of) free choice. Yes, it was her choice to put wrapper in bottle that had wasp's nest. No, she is not responsible for bee stings that resulted in perceived end of life of her infant. These questions of responsibility are distractions away from simple truths.
The same works for God and the nature of evil. If God knows everything that will happen if he makes the universe doing this and that, then he also knows that evil will happen, should he be held responsible for the evil of the world in that case?
This is where 'what' would happen falls apart in way that Knowledge addresses and purifies with ease. As if what 'will' happen is matter of doubt, unforeseeable. That which is happening, but appears as 'will happen,' in short explanation, is the dream of separation from Source will end in nothingness of which it came. The perception of death will come to an end. That will happen because in reality the separation never has happened, so its undoing is already done. Within illusion that asserts separation is still happening, it is a matter of time (illusion within illusion).
We are responsible for seeing illusion in place of truth, and insisting truth cannot effect illusion and have any influence on 'all the evil that has been made manifest.' That is our responsibility. While the burden is perceived as overwhelming, the simple truth is evil can be undone when illusion is brought to truth, and NOT kept hidden. At this level of understanding, things can get a bit complex in terms of explanation. Thus short explanation may no longer be plausible. While illusion appears to be hiding the truth, Free Will is perceived as not possible. Thus the illusion of free choice is born as way for imprisoned will to have 'way out.' Without the injection of freedom of choice within the paradigm of separation, the 'reality' is the world is playing out an elaborate chain of cause and effect based on a cause that is an illusion, or distortion, of will. It is perpetuating myth or understanding that the will of a creator can be unknown and/or separated from its Source.