Once an ACS group is created, its coordinates are tied to the selected target. Galaxy, system and position remain fixed, and joining fleets must match that same destination.
How does this rule work?
Inter-War validates coordinate consistency when additional fleets join. It is not enough for a fleet to fly nearby—it must join the same group and match the established target.
What exactly does the server validate?
If you want to attack different coordinates, creating a new group is safer than treating the existing ACS as a flexible target template. A fixed target protects synchronization of the entire joint attack.
How does this affect the mission?
This matters especially when several similar targets exist in one system. Choosing the wrong position can prevent an otherwise correctly timed and composed fleet from joining.
When does it matter?
ACS does not create a separate, looser combat system. A joint attack still uses normal player protection, attack limits, target validation, fuel and fleet-slot rules. The group only synchronizes several valid fleets into one battle context.
Common mistake
Before joining, verify the leader, target, object type and planned battle time. Most problems come from trying to join after the target changed, from outside the required alliance, or with a fleet that cannot arrive at the required time.
Related FAQ: Are a planet and moon the same target in ACS? · How does ACS arrival-time synchronization work?