When playing my first few games I wished that all my ships that I send on the attack would jump at the same time rather than piece mail. After some digging in the controls I found that the command to toggle that wasn't bound and then realized it's part of the move button. When I tried to use the group jump I've run into problems though. I have my main fleet set as group one and I select them when they are all in the same system and right click the move button to change the phase jump option to "All grouped". Yet when I then go to jump to another system about half of the fleet jumps as soon as it hits the gravity limit (term?) while the other half waits and then jumps as one.
Not sure if there is something different you have to do to set the command or is it just currently not working correctly.