From my experience with robo groups, it's looking like it's going toward a full-on falling out, unfortunately. I would keep a close eye, because what you are describing eventually does lead to biting, which may not be obvious (it can be a nip on a bum, or a bite on a stomach). Look for any signs of blood on objects in the cage.
Falling out like that is pretty normal, sadly for us and for some of the hamsters, but they should hopefully all be okay living on their own with cozy homes and more toys to compensate for their "alone-ness"
You can always try either of the hams in the current pair with Pickle on a neutral territory, such as in an empty bin. They might get along!