While you can fix any child seat reasonably well in a normal car, this is not the case with motorhomes. Motorhomes, on the other hand, usually do not have Isofix (especially the older models, of course) and the seat cushions are cut straight because there is a box underneath for storage.
In some cases, an Isofix device can be retrofitted by the dealer. For final clarification, please contact your Dethleffs authorised dealer or service partner.
Children younger than 12 years or smaller than 150 cm therefore need a suitable child seat in the motorhome. They must be fitted in the seats where the respective belt (three-point or two-point belt) is approved for fitting the child seat. Depending on which child seat you have, this is attached in the motorhome: Always make sure that you guide the belt through the notches provided in the seat and that nothing is twisted.