This idea is stupid, I will be insulted, joked at and hated for it but...
Could our heroes meet? Picture this- the hero of Tython fighting alongside the emperor's wrath- cipher nine kicking butt alongside the galaxy's greatest smuggler- the consular and Darth Nox fighting armies- havoc squad and the galaxy's most wanted bounty hunter mowing down foes. The 8 heroes unite to save the Galaxy....
Or - a better, more plasauble Idea:
The player pretty much becomes the next Revan. During an assault on the empire their leader defeats our hero and freezes him in carbonite. Perhaps you are woken up and they are trying to turn you to their faction, but you escape...