User blog comment:Sky-Dragoon-Twilight/Weisslogia and Skiadrum, Alive or Dead?/@comment-25111584-20141209101442/@comment-9595671-20141209130604

That makes logical sense, Doranbolt did fool everyone with it until Pantherlily found the hole in his logic about being Mystogan's disciple.

And Grandeeney proved Dragons can learn other forms of magic as she's one of the 14 characters that use telepathy magic. So its very logical that they used Memory Control magic.