There was 8 sleeper ships. 5 ones launched, 3 on standby. When the Bretonia, Liberty, Kusari, Hispania and Rhienland made it past the blockade, the other 3 were deserted. Then the Nomads showed up and the sun goes boom. Because of some guys who were supposed to move all 3 sleeper ships to the launch pads but was too lazy, one of them was left on the dark side of Pluto. The nomads then launch that energy thingy at Sol and it goes boom. Only 2 of the ships were destroyed do the spare sleeper ship was launched by the guy who survived to go to Sirius to warn the Alliance of the Nomads. The Nomads were probably elsewhere buggin' the hell outta ET for 200 years or something, long enough so that the people in Sirius were strong but forgot about the Nomads as they never bugged tham at all. The Nomads waited and waited and waited and... (You get the idea) ...until the Rheinlanders find the artefacts. Sinclair finds one of Planet Pygar and that theif with the space cigarette steals it. He goes to deliver it to some other guy on Freeport 7 and the Nomads notice this. They go to steal it back so that the Humans can't get rid of them. That's when Trent and everybody get's involved.
The Sleeper Ships Are-
Bretonia - UK
Liberty - US and Canada (nothing against Canada)
Kusari - Japan
Rheinland - German
Hispania - Hispanics (makes sense )
Other Sleeper 1 - Backup
Other Sleeper 2 - Backup
Other Sleeper 3 - Backup (used for the guy to tell Sirius)
I'm guessing the backup ships were mixed.
This may leave some quiestions unanswered, but it fits in to all that's there.
"Sure, as long as I don't get shot at, held at gunpoint, skewered by giant alien shapeshifters, have to jump out windows, fight off unfriendly nomad incubii"