Time is relative in special relativity. Things do not happen at the same time or the same order. Say FTL jumps are instantaneous for the ship in their frame, th

Time is relative in special relativity. Things do not happen at the same time or the same order. Say FTL jumps are instantaneous for the ship in their frame, this means that ship moving fast will have a different view about when the jump happens. Ship 1 FTL jumps, transmits message to Ship 2 that is moving relativistically, and then Ship 2 FTL jumps back. Ship 2 can arrive before Ship 1 left, creating a paradox if they give them the message. This assumes that FTL follows relativity where physics are the same in all frames. If it happens in fixed frame, then there isn't a problem. But that would break physics; I guess FTL would break physics too. We would either need to give up on causality and except weird things happen, or give up on FTL and accept light speed as the speed limit.