Lufthansa new lugage rules

Has anyone flown on Lufthansa recently and had experience of their new luggage requirements (since 1 June)? I am flying to Germany with my husband and baby and have been told we can take either buggy OR car seat. We have an allowance of 3 suitcases (weighing 23kg each) plus buggy for free. We want to take 1 suitcase of 23kg plus small buggy plus car seat weighing 4kg. However I have been told by Lufthansa that I can only take the Maxi Cosi if it is in a suitcase. I don't have a large enough suitcase. Does anyone know if they are strict with this rule? I am already saving them 46kg by only taking 1 suitcase so thought we should be fine with a 4kg car seat instead but apparently not.