Board Thread:Poll Archive/@comment-24095889-20140415141927/@comment-3076833-20140710214400

> Although, the fact that they have the same surname would suggest that they are related somehow o̶r̶ ̶p̶e̶r̶h̶a̶p̶s̶ ̶m̶a̶r̶r̶i̶e̶d̶  Anyways, we know that they must have some significance to each other, or they wouldn't be sold together, right?

I think the fact you are looking for is the one that Rin and Len has the same voice provider. If I re-call my VOCALOID history correctly they only brought Asami in to do a female voice (Which would eventually be Rin) and it wasn't until Crypton found the opportunity to record Asami in a more masculine tone that Len became a thing.

That's how they're connected, and the sole reason that there is no official title for such a relation is for the sake of creativity in song writing.