I will not rule out that possibility, but I've some doubts about it: Ketches have jump drives that allow them inter-system travel. On the other hand, it would seem that Skiffs are just using a stealth system for moving around, deactivating it just before a drop and re activating it just as the leave. If the Skiffs are indeed escorting the Ketches, does that mean that the Skiffs also have jump drives? Personally I just assumed that the other Skiffs flying around a Ketch during an event were meant to represent that the Fallen were performing multiple drilling operations at once, with the other Skiffs supposedly landing on other areas unreachable areas with their own Glimmer Drills (those flying devices appearing during the Extraction Crews and Fallen Walkers public events). If you think about, it would be rather excessive/wasteful for a Ketch and 5 Skiffs to be deployed just to escort another Skiff. Furthermore, I think the Skiffs ability to act as an escort is rather limited given that it's weapons are mainly designed for clearing out the drop zone for its troops. And just for the sake of discussion, let me throw an extreme case: if a Ketch makes jump close to the planet's surface and immediately deploys 6 Skiffs (each with its own troops and a Glimmer Drill) to 6 different landing sites, then could we assume that when deploying Fallen Walkers for defense, a second group of 6 Skiffs with a Walker each, were deployed after the landing of the first group? In such case we could assume that the number of Skiffs that a Ketch carries could be at least 12.