I have a 2000 328i E46 sedan without isofix and am checking if it's possible to add it.

The system itself looks simple enough, 4 brackets and 4 bolts that bolt into the chassis:
https://www.realoem.com/bmw/enUS/sho...diagId=72_0374

However, digging deeper into realoem also shows that the rear seat cover is different and has little trim 'hatches' that cover the brackets:
https://www.realoem.com/bmw/enUS/sho...diagId=52_2339

I'm wondering if changing the seat covers is absolutely necessary. Has anyone ever tried to install this? What are your experiences?