Having been an independent for over 25 years, these documentations issues have never interested me except for the documentation in the maintenance manual.
I had assumed that MB dealers shared their records with a central computor.
About 7 months ago I purchased a 97 540i from a wholesaler in Houston. I had a good friend there with an independent shop look at it before I bought it (I bought it on ebay). I also checked it out with Carfax and with my friend at a BMW dealer. My dealer friend was able to find out that all the services had been performed by the selling dealer and that the car had been there for 19 job operations including all the maintenances. The were able to tell me that a woman had owned the car and serviced it at the selling dealer. I also found out that she traded it there.
I am a little surprized that BMW might keep better records than MB.
Bosch Master, ASE Master, L1
33 years MB technician