Jesus, guys, you arguing about so obvious things!
Before Dreamfall release Lady Alvane was 100% April, and here the simple logical proves that that can not give any doubt for a logical persons:
1) Story starts as Lady Alvane's narrative. Then story continues from April's perspective.
So its quite obvious that Alvane tells story about April from April's POV.
No try to guess, how lady Alvane could have know even thoughts of April and every little step April? Right and the only answer - because Lady is April and she told her own story to kids.
2) April is a shifter, and Alvane is a shifter (which is obvious in scene where Lady opens portal for April). There are not so many shifters around, even Draic Kins cant shift (so crazy irrational theories about White lady should be thrown into trash bin)
3) Lady Alvane had Stark books only on shelves, which proves that she is from Stark just like April.
4) Old Crow in the end is good friend of Lady Alvane, and there is no doubt its same Crow that was a good friend of April.
So how can anyone doubt that Lady Alvane is Old April after this? So many obvious clues pointing to this obvious answer.
5) Entire story people (especially Cortez) Tip April that both worlds will merge, and that April will paly important role in this merged, but this will happen not now yet. in story of Alvane she points that Worlds already merged and April's story is most important story of balance (which give a tip for sequels plot line).
This kinda clearly shows how entire TLJ plot will end like - worlds will merge, April will get old and will start to tell stories about her past to Kids. THATS SO OBVIOUS!
6) When April and Lady Alvane talked to each other, Lady gave another OBVIOUS CLUE that she is april - She said she is called Alvane now, but she wasnt before.
7) And in same time as #6 April give another OBVIOUS TIP for slowpokes that Lady Alvane's face seems familiar and april feel trustfull. That just a tip for those, who aint understood yet for that moment that Lady alvane is April.
8) White Kin is real mother of April, Lady Alvane is obviosly from Future, little white kin sister is not from Stark (so why would White kin keep Stark books on shelves? lol) so by the balance, stop even think that Lady Alvane could be White Kin! She could not be! (even if previous 7 proves not enough for your irrational heads to understand thaat Alvane is April) Also stop thinking that April could have parents with Surname Alvane! No she could not, White kin is her mother and she have no Surname, so the only way for Lady alvane aka April to get this surname is obviously from Marriage (Okama razor should keep you away from speculations about fake id or something like that)!
9) In game resources Lady Alvane called Old April! Why would they call her Old April?
DAMN THAT HARD ONE! Maybe Alvane called Old April because she is in fact Young Cortez? LOL)) No, damn it, she is called Old April because she is Old April and there are 8 more quite obvious reason for her to be Old April.
And for those whoul think "why she didnt tell here truth?" maybe because she wants everything to happen as happened before, and because when old Alvane was young April she already met her old self and herd same words, so when time have come for her to meet her young self, she did same thing? Isnt that simple?
Ok now we advance to 2006 year, to Dreamfall days:
1) For those, who still was refusing obvious facts that Lady Alvane is April Alvane, Rognar Developed character Kian, called him specially Alvane and set beginning of romantic relationships betwen Kian Alvane and April, to give funs a clue of how April became April Alvane we seen in TLJ.
2) To avoid misunderstandings like ideas that Kian and April could be brother and sister, Rognar even made Kian a black, so no one idiot could tell that they could be brother and sister... (but looks like his attempt to give another obvious clue failed, since some irrational people believes that black guy and purely white girl with no signs of black genes, could have same Parents... ignoring the fact that real mother of April is White Kin [dont get me wrong it just biological terms, nothing racistic]).
3) Game ended with Twin Peaks and LOST style of cliffhanger, as intrigue for another sequel. Thats quite obvious too.
Aprill seems to be killed, bud damn, it simple to understand that she is no dead, and this plot twist was specially developed to make you all want a Sequel so damn hard. But it surely obvious that april would not die, she will survive, or she will die, but then will be ressurected by magic, or by Zoe's Dreamer|storyteller superpowers (it seems that dreamer aka storyteller is kind of specialization like Shifter, but when shifter makes portals, Dreamer tells story in Void, which becames a reallity outside the void, so i bet 10$ that Zoe special skill would be revival of April by power of word). Whatever. It just a CliffHanger. It is there to confuse you, but Rognar is smart writer and he will surely not retcon main plot line about old April Alvane from TJL and reunion of worlds planned back in times of 1st game.
He just make forced many of doubt in obvious thing. Trick from Social psychology. Death of April is obviously fake, lie for your eyes and plot Device to force Kian to change the sides, betray his people and take April's side.
You are guys soe easility manipulated by single cliffhanger & some tricky comments of Rognar (who surely interested to keep intrigue for a sequel, and purposely seeding doubt in obvious facts) so you can start to doubt in any obvious facts.
Turn you rationality on!
Lady Alvane is April Alvane and no one Else. Obviously than obvious. period.