Prince Xizor and the Black Sun would make a terrific villain and organization for Luke, Leia and the former Rebels to fight in the new Sequel Trilogy but, alas, book canon dating back to the mid-nineties places Xizor's defeat and death before JEDI (circa 4 ABY) and he and Black Sun can't be used unless the Shadows of the Empire storyline is decanonized and dumped so they can be used in the future films. SOTE is a pretty beloved and accepted piece of non-filmed SW lore and I doubt it would be shelved and forgotten so easily.
By fanboys - if Disney wants to recycle the characters, it will without a second look, the money you spent on those books came in and was spent years ago.

Luke's teenage son raised by aunt leia who has daughter. Han and Luke apparently died years ago on secret mission. New sith lord arisesand kids engage. Turns out to be Luke who is brought.. back.from dark to light by his son. Puss off all the old.guys like me.but since.you are targeting kids 7 to 25 you are set