"is in relation to" is a correct phrase in written English.
You could use it to refer to a connection between two things. For example, "His success is in relation to his hard work."
That is how the world is in relation to books.
Everything is in relation to how it makes him feel.
The "wide net" that concerns Williams is in relation to these "certain other offences".
It's understood the raid is in relation to a leak about the National Broadband Network.
The question is where the line is in relation to the ball.
The most worrying manifestation of this is in relation to the kettling of young children.
"And a lot of that is in relation to the Internet".
One of the ways I think about smacking children is in relation to smacking adults.
Most of what Gore says in public is in relation to Bush, rather than about himself.
An issue in China with renewable energy is in relation to connection to the grid.
And that is in relation to the developers' notion of affordable, at 80% of local prices.
