Regarding your first paragraph, Assuming you are talking about special (or general) relativity, Just because simultaneity is relative doesn't mean that before

Regarding your first paragraph, Assuming you are talking about special (or general) relativity, Just because simultaneity is relative doesn't mean that before/after is in every case. My limited understanding is that which of two events happened first is not relative to the reference frame when something moving at or below c could reach one event from the other. My understanding of that could be missing some details or be wrong, but I think that is how SR works?