George Geftakys' opening in France came through Marguerite Harrison, who knew Paul Vaiss and was very familiar with the T. Austin-Sparks ministry in France. Paul's mother, Madame Suzie Vaiss, visited Fullerton several times and became friends with my mother, Sister Mayo.
We have scant information on how the situation developed in France after 1990. It seems there was a disagreement between G. Geftakys and Paul Vaiss, most likely over George wanting more control over the Assembly. The result was a split, with Paul's mother, Madame Suzie Vaiss going with the new Assembly which was under George's jurisdiction.
We do not know when the split occurred, but the Believer's Prayer Letter for March, 1998, announced a holy convocation in the new Assembly in France for guests from England, Spain and Holland. "Kristin's Story" mentions Le Vesinet, so we assume that is the location of the group that split off with George from the group in Paris. A 2000 Believer's Prayer Letter mentions that an MTT team was going to France. Chatou was mentioned in a Prayer Letter, perhaps as an outreach from Le Vesinet.