Here are the parts pertaining to Shantel:

And how about Shantel VanSanten as Haley’s sister?
M.S.: Yeah. Where is Shantel? Shantel, talk to Korbi about your character.

Do you and Haley like each other or are you sisters who cat fight and steal each other’s clothes?
Shantel VanSanten: Well, we steal each other’s clothes in real life. Joy [Galeotti (Haley)] came into the make up trailer one day and was like, I like your shirt (my real life shirt). So she says, Can I wear it on the episode? I’m like, Sure. So I took it off and let her have it.
M.S.: What she’s not telling you is, then that shirt goes into the wardrobe trailer never to return! She went home in her bra. And Joy’s like, Thanks!

Awesome.
S.V.: But yes, I play [Haley]’s older sister. I’m a photographer. And I think we both have that artistic side. Her being a singer, we have that same mentality in common and I think we’ve always been close for that reason. But I got married when I was younger, so I have a whole other relationship and whole other life. I come back to Tree Hill just like a lot of people go home to kind of figure life out. And I think that [Haley] becomes my best friend, the person that I would call about everything.

Nice.
S.V.: Yeah, I think that it’s fun to bring [Haley]’s sister in, because you end up seeing a different side of Haley. You know what I mean? You’ll see different things you maybe wouldn’t have seen before because her sister’s around and there’s that sister bond and you tell each other secrets and expose things you wouldn’t have otherwise.

Me and my own sister are so close and Joy talked to me about it, she wanted to know what my relationship with her was like and we discussed little ticks that sisters have and it’s really been awesome. She’s awesome to work with.

So, does your character come to town solo, even though you’re spoken for?
S.V.: I come for Jamie’s birthday. But I think when you’re in your 20s, you go through stuff. Is my life going in the right direction? Am I doing the right thing? Is this what I want for the rest of my life, with everything, [you question] your job, your love life. So I think maybe she comes to town trying to figure some things out and through her relationship with her sister and everybody else in Tree Hill, hopefully she’ll find the answers.

Who else in Tree Hill will she be close with?
S.V.: I get to collaborate with Sophia’s character Brooke, because she has a clothing line. There are a lot of relationships that she gets to come back to and be a part of that world.

Might she have a love interest even though she’s married?
M.S.: I’ve never endorsed that. But, having said that, if issues arise in her marriage, then that is interesting to me. If someone is genuinely not happy in their marriage, when is it okay to start looking elsewhere? I don’t know if that’s necessarily the road we’ll go down with Shantel’s character, Quinn, but as a storyline and as drama for the show, I think that’s interesting.