Negating or ignoring movement from a physics collision

Thanks for the explanation; I have nothing on the Blueprint yet as I am not sure which event I can use to determine if there has been a collision between A and B. The only event I can find is the Hit Event which seems to be too late from the explanation above. The explanation requires the ability to determine a collision prior to the Hit Event which I am unable to locate.

I think I am missing something fundamental within your answer, apologies.