It might be a coincidence, but to be honest I believe there are too many similar design aspects to Tntina and Haven. I think they could very well be related. I also just think it would be funny if Haven was just like Tntina, but got hit by a truck causing severe brain damage (and an ugly face), and causing her to literally "go wild".
Firstly they both have brown hair and blue eyes, as well as, obviously, white skin. I did think Haven actually had green eyes, but zooming in lead me to the conclusion that she, in fact, has blue eyes.
As you can see, clear as day, blue. You may also notice that she has frekles, unlike Tntina, but I found out it has less to do with genes and more to do with exposure to UV light/sunlight. Which, obviously Haven would be more exposed to.
But they also have a similar color scheme. Red and golden/yellow. They even both have crop-tops and similar looking pants. Her "midnight" style is also quite literally just Tntina's shadow style.
All of this might be a design choice and perhaps just reusing old designs (alao known as laziness), but I'm not sure, which is why I'm including them anyway.
Her being related and having a Shadow style could mean she supports Tntina in being part of Team Shadow, or, because Team Shadow was the team formed by the I.O. to try to stop Midas, it could therefore mean Haven is working for the I.O.
In their original styles, they both also have 2 hearts and 1 star.
Shadow Tntina also has a knife/dagger tattoo and Haven has a dagger. Another coincidence.
The dagger tattoo and dagger are also both on the same side of their body. Another coincidence.
They also wear fingerless gloves. Which is probably the final coincidence. Although on the other arm of Tntina's shadow style, there are bats, which could be a reference to Haven now. Or that bats are coming, which would be cool. Even tho they probably wouldn't do anything lol.