User blog comment:FairyRaven/Fairy Tail Chapter 408: The Definitive Demon, Review and Commentary/@comment-24277053-20141110135803/@comment-122.26.34.97-20141110212345

Contradiction or lack of info.

At least Silver knows Minerva during Sun village arc. Silver told Gray Info about Tartaros. It is clearly unwritten event.

I honestly don't trust Mashima at all. True answer is unclear.