honestly? like most MMORPG's unless you're playing with friends whom all have different classes than you, you'll need to divorce your character from their "official" storyline anyway- in multiplayer rp, you have to account for multiple heroes often doing many of the same things, since you're divorcing it from that anyway, rpers should have no trouble with the necessary suspension of disbelief- when you roleplay, your character isn't THE hero, they're A hero.
I remember from World of Warcraft, my Paladin had almost nothing to do with the Sylvanus ICC instances- or the main raid that i did. Storywise, he was part of a heavy branch assault going after the nearby cathedral of darkness, prior to that he didn't level throughout Azeroth, he spent 1-60 as a part of the Argent plague lands fighting after having been stranded outside of Silvermoon.
All of the above takes only the lightest inspiration from his actual experiences, and the same goes for the stories crafted around the characters of my friends. I retooled things to fit into a multiplayer role playing perspective.
My personal story?
My Sith Assassin and Jedi Sage are going to be brother and sister (lightside / darkside respectively- so much duality, having been split up at a young age- the families daughter ending up with the jedi order- and her brother the force sensitive slave), My Operative will probably be a cousin if i can arrange it properly- her family having assimilated into the Empire.
I haven't really figured out sons and daughters yet- and I'd be more likely to make adopted ones anyway.