The forum you are looking for is lower down the list and clearly labelled as being for realms lore.
Like Storm Silverhand, what happened to her?
-We don't know. The FRCG was light on a lot of information, so we don't actually know Storm's ultimate fate. Same thing with plenty of other NPCs.
I'd like to know what happened to the seven sisters and whether my FR campaign can be generally cannon if I added them in (like their grave, or ghosts, or whatever).
The word "canon" should be utterly expunged from the English language, or at least from the lingo associated with the FR. Moreover, if such a word is a necessity for a fictional world, then remember that the 4E Realms are ambiguous enough to let you make you own "canon".
For those among the Seven Sisters who are counted among the dead and gone--with little lore to explain why--the very lack of lore gives more than enough room for you to claim that "in truth" they do live on in secret.
As for those few whose deaths were more elaborated on in novels or adventures, the reasonings for their deaths are often so absurd that you can just as easily re-write them for your own campaign, with the reasons for their continued existence being only half as silly as the reasons for their forced demise.
Adventures like Shadowdale play out as the DM wills them, and no pre-planned script or prologue is a requirement for how events will ultimately turn out for you. As for the Seven Sisters who were "killed" or noted as "dead" in novels....well either use your creativity to overrule the novels, or if that does not satisfy you then just tear out the offending pages and burn them.
SPOILERS...
...and personal suggestions for undoing them
1) As far as Shadowdale: the Scouring of the Land is concerned:
-If Syluné Silverhand can be laid to rest in an adventure prologue by an upstart NPC cleric of Shar, then she can just as easily be resurrected in the epilogue of the exact same adventure by an upstart PC cleric of Mystra (who coincidentally earned exactly enough XP in said adventure to reach 13th level, which coincidentally gives her access to the 7th level resurrection spell, and who coincidentally had an unimpeded opportunity to loot Syluné's ashes from her tomb earlier in the adventure to serve as her remains needed to fuel the spell....all without the slightest alteration of anything written in the adventure by the DM)
2) As for the non-interactive medium of novels, such as Ascendancy of the Last or Blackstaff Tower, I give you these suggested words of restoration to undo and revise things they have wrought;
-Krehlan Arunsun was misled about his mother's fate, for in truth she wandered the realms namelessly for an age, compelled by her grief to abandon the life and legacies she lived as Laeral, wandering aimlessly to bring a spark of hope to dark corners of the world.
-Qilué Veladorn was slain only in part, for only her drow essence was destroyed by the Cresent Blade, and in truth she was reincarnated amidst the shattered Ladystone, as a full grown human woman of silver hair and the full semblance of Elue and Dornal.
3) As for the Luruar entry in the Forgotten Realms Campaign Guide, here is another verse of undoing, for those who wish to keep the High Lady in their campaigns:
-Alustriel's passing was false, and entombed she merely slumbers in stasis, to be awakened again only when the shadows have all but consumed the light of the north, and the hour of need is most dire.
The word "canon" should be utterly expunged from the English language, or at least from the lingo associated with the FR. Moreover, if such a word is a necessity for a fictional world, then remember that the 4E Realms are ambiguous enough to let you make you own "canon".
-Something has to denote the officially supported incarnation of the setting, as opposed to unofficial (ie, fan) interpretations of it.