Hmmmmm .... I did notice that she didn't do forewards/afterwards for all of the books, but hadn't considered it in light of when the books were re-released. Was it only the earlier ones that had Gregory's remarks? If so, perhaps the publisher realized she wasn't doing Seton any favors, and stopped having her write forewards. I certainly didn't miss them!!
Not sure, after My Theodosia the rest of the Seton books I read all were older editions via library.