You can definitely move cameras from one network to another. If it was not allowing it that would be due to no destinations networks being modern combined networks with the camera sub group type.   In that case you'd need to update your legacy combined networks to modern combined networks following the process I cover here https://docs.google.com/presentation/d/1fFjA-HCNB7KE03bUgCGINoNqVMVSumlF4Tjo-bUH9aE/edit?usp=sharing   ... View more