One day, the idea of Vinyl being Rarity's cousin just popped in my mind.
Apart from both of them being unicorns and having the same white coat, they both can be defined as artists in their own fields, (Also, it is obvious that Sweetie Belle talent will have something to do with music, just like Vinyl). And finally, the first time Vinyl appeared on the show was in the chapter 'Suited for success.' Maybe Rarity asked "her cousin" to play the music for her fashion show.
What do you think of this?
I know is not enough to say they are related, but the idea is interesting at least.

1783363 I think Octavia's her cousin

1783363
Well, it could be really good, and it had already been done in a fic (heck there are fic in which Rarity is Vinyl in disguise or the opposite)

on the other hand, there is the really intriguing connexion between Vinyl and Twilight's family. (cousin or half-sister or simply sister) due to how close she looks like Shining and that she was playing at his wedding....

In the end, if you come with a good story about them, you can make her relative with any pony (I made Vinyl the (adopted) sister of Applejack )

1783376 Interesting, I'll have to read those fics.

1783363 Personally, I think Vinyl Scratch is Rarity and Sapphire Shores' magically conceived daughter (who visits the present day Equestrian world from the future, and that's why she doesn't appear very often).

THINK ABOUT IT.

1783385 That. Is. AWESOME!

1783394 I know.

1783363 It does sound intresting. Though I think more people will consider her a cousin of Twilight and Shining Armor because of her mane style.

1783376 Funny you should mention about the Twilight thing. I just happen to start writing a fic based on that :3 Changeling though. THE ANSWER IS CHANGELING, GUISE! Shameless Whoring!

1783363 I say DO EET!

1793110 I think I will implement it in one of my stories,.

1783363 You do know she has an off-white coat right? Its not completely white. But it is a good idea!

1783376 Do you have a link to a Rarity disguised as Vinyl or vice versa fanfics?