User blog comment:IamJakuhoRaikoben/Chapter 366: 1000 Souls, Review./@comment-4449950-20140111003333/@comment-7418318-20140111123224

@anon: I'm not saying it's impossible, but there are other explenations for that.

Connsidering how Grandeney "visited" Igneel earlier in the story it's not too far-fetched to assume she might have done so too from time to time before they went into hiding. If she came personally she naturally would have taken Wendy with her. And even if she only initiated remote communication, she still might talk proudly about her foster daughter.