Blueprint event cannot be overridable and so virtual. Event didn’t have internal code, it is just an event. If you have class ChildClass inherited from ParentClass where ParentClass has event named MyEvent, then you can call your event from ChildClass using ParentClass::MyEvent();
Example:
void ChildClass::DoNoSense()
{
if(2 + 2 == 5) ParentClass::OMG_Event();
}