is vitani and kiara sisters?

No. Because the movie does not state such things.

Remember that Nala certainly isn't the only blue-eyed lion in the world, nor are anyones the only lions with a certain fur, manyoya colour.

Vitani's looks could've come from her father which most likely was not Scar, for Scar was not Kovu's father and Vitani and Kovu are zaidi than likely litter mates.

And, lion cubs look zaidi au less alike also in real life even with no blood relation to each other.

Again, no - Vitani and Kiara are not sisters, Scar is not Vitani's father and Nala did not marry Scar. None of that, in anywhere but fanfiction stories.

No. Just no. Why would Nala EVER mate with Scar? She was always with Simba.

Umm..No! Nala only has one child and it's Kiara.
Vitani is not close to Kiara as a relative.
Vitani maybe Scar's au a bila mpangilio lion that Zira mated with.
When Kiara and Kovu are married then she becomes
Kiara's sister in law.

Nep. Scar is Nala and Simba's uncle. durr.
BTW, Their family mti is so complicated.
Scar and Mufasa are brothers so that's why Scar became Simba and Nala's uncle. Scar has 3 children (1 is adopted, Kovu..or maybe....also Vitani so that will be 2). Kovu, Vitani and Nuka are suppose to be Nala and Simba's cousins but since they we're exiled and outlanders in that moment they never had that relationship (Just like two people didn't know each other). But they started all over again in the ending of Lion King 2, well.. DUH! I told wewe it's complicated. But people this is only MY OPINION, no big deal please ^^

wait..! What am I crazy? saying all of those family mti above?! They're lions! durr..., silly of me, I wasted my
time. -_-

Once again..it's a NO.

My answer is that they are half sisters. Vitani does have a fur, manyoya tone similar to Kiara's but also Similar to Simba I say Vitani's father is Simba but her bright blue eyes suggest a genetic thing due to Scar
being Simba's uncle. Her scar shaped nose came from her mother.
As well as her other outsider features.I did sense some sexual tension between Simba and Zira meaning her and Nala ' s rift could not be only over Kopa but A secret mate ship between Simba and Zira in order to produce a cub fit for royalty because of Nuka being a disappointment. But Vitani ended up being a girl. So she had to come up with another plan.

No. Nala nor Simba are in any way related to any of Zira's cubs except through marriage. Nala wasn't Scar's mate. Scar doesn't have any known mates au cubs. There is a deleted scene where Scar tries to get Nala as his queen. But she refuses. Which is a clue that Nala × Scar wouldn't work. Simba isn't Vitani's dad either. Zira is her mother though. Vitani doesn't call Nala mom. She also doesn't call Simba au Scar dad. Vitani most likely gets her blue eyes from early story ideas au her father. Almost every simba's pride novelization including a Disney Book which I bought myself included Zira with blue eyes. The book i bought also included the deleted scene Another Cub. And the one with Kovu's original first appearance. There was also an idea where Zira had green eyes. In what looked like a sketch near production showed Zira holding Kovu with what appeared to be zumaridi, zamaradi green eyes. Also I've heard that Zira's eyes were supposed to be green like Kovu's. Vitani's dad could also be where her pink nose came from. And her lighter color. Scar nor simba is most likely not her dad for zaidi than one reason. I'll be happy to give wewe the short list.

Reasons why Scar is Not her dad.
(1) In the deleted scene it says Scar chose Kovu To Be His successor as a dying wish.
(2) In the song Not One Of Us the . The lyrics say born in grief . Raised in hate. We know where raised in hate comes from. But born in grief suggests the possibility Kovu was very young during either Scar's death au his real dad's but I'll suggest Scar's .

(3) Vitani and Kovu are most likely littermates. Scar is NOT Kovu's dad. His eyes aren't the same shade of green as Scar's. Also Kovu has a completely different fur, manyoya tone and mane color. He only looks a little bit like Scar to arouse fear in Simba. Also it's stated kwa nearly every Outsider that Scar isn't Kovu's father.

(4) In a deleted scene from the lion king. Scar wanted Nala as his queen. Not Zira which I can probably see why. Zira wasn't even in the Pride at that time. Meaning she probably had only recently come in just before Simba came back.

Reasons why Simba isn't her father either.

(1) Why would Zira EVER mate with Simba? She hates him. Also if Simba au Nala were Vitani's parents I think Zira would probably have killed her off instead. Plus wewe seen how wacko Zira is over Scar considering he doesn't upendo her but wewe know.

(2) Incest. If Vitani were Simba's . Which she is not. Then considering her and Kovu are most likely littermates. That would mean Kovu is to. Which is the whole reason Scar isn't Kovu's father. So him and Kiara aren't related. There wewe have it Vitani's father is an outsider male.

No because Vitani is Scar's daughter and she was born in the Outlands and Kiara is Simba's daughter and she was born in the pridelands

Vitani is the daughter of Zira. Kiara is the daughter of Simba and Nala. I'm pretty sure they're not sisters kwa blood.
They are sisters-in-law, though, if that counts.

Also, why on earth would Nala ever mate with Scar?

No, Vitani is Scar and Zira daughter and Kiara is Simba and nala.

No. Vitani is not Simba's daughter, nor Nala's.

Reasons why Simba is not Vitani's father:

1.) Why would Simba ever mate with Zira? She hates him. If Zira was Simba's mate then that would make Kovu and Kiara half-siblings.

2.) The timing dosen't make sense. In "The Madness of King Scar", Scar dosen't have a mate, even if Nuka was conceived after the song and if Vitani was conceived after "Can wewe Feel the upendo Tonight", then 1.) Nuka and Vitani would be the same age. 2.) Vitani would stay in the Pridelands when Simba became king.

Reasons why Nala is not Vitani's mother:

1.) Why would Nala ever mate with Scar? If Scar is Nala's mate then Nala would be Simba's aunt.

2.) The timing dosen't make sense. In "The Madness of King Scar", Scar dosen't have a mate, even if Nuka, Vitani and Kovu were conceived after the song, then Nuka would be the same age as Vitani and Kovu.

Again, Vitani is not Kiara's sister. Vitani's father was an unknown rouge lion. When Kovu marries Kiara, Vitani becomes Kiara's sister-in-law.

vitani and kiara are real sisters nala just gave away vitani to zira for some reason