The installation was easy and fast. I bought a bicycle suitcase (M-wave) and to those attached to the coupling set by Klip Fix. It is secure not just as when the case would be mounted directly on the carrier - but tight enough (has some play) and so I can arrange if needed the suitcase quickly and the child seat mount without the suitcase is in the way ;-)
If the case is filled something - he no longer scrambles.
A nice touch with the adapter - The purchase was worth it - had to take him to buy for my mother now.