I have an AMG Sport s212 and was looking at doing this. I found the part numbers from MB and the code needed for ordering as optional extra. However, when I enquired with MB spares they said the parts are not available. Also, I could not find any secondhand in 12 months of searching.
As for retrofitting, after looking at the parts diagrams, I thought it would be relatively straightforward to fit the seats, but thought the seat-belts could be problematic do to overhead fixing points.
Ultimately I kind of gave up on the idea as I read the 3rd row is fairly useless for all but the smallest of children anyway.
Be interested to see if you have different thoughts/experiences.
I imagine that MB will not supply the parts over the counter for a retrofit conversion because of the safety implications should they not be correctly installed.
As said, they are only fit for small children to use and then you have no usable luggage space.
If your car is a later model with the bluetec tank then even if you sourced the parts you would have no space to fit them. The adblue tank sits where the third row of seats would need be fitted.
If your car is a later model with the bluetec tank then even if you sourced the parts you would have no space to fit them. The adblue tank sits where the third row of seats would need be fitted.