Changing iTunes store ID to match Apple ID
I setup an iTunes store account long before I had an Apple mobile device or an iCloud/MobileMe Apple ID. As a result my iTunes store account is linked to a non-apple email address whereas my Apple ID uses an Apple email.
This hasn't really caused an issue until now, as it seems I'm unable to set-up Family Sharing for Apple Music (presumably because Family Sharing uses my iCloud and Apple Music is linked to my iTunes account).
Is there a way of changing my iTunes store account so links with/uses my iCloud ID?