Can Immobilizer be Coded to Block Old Keys?

[Manolito]

Last week a burgler broke in and stole both keys, took daughter's pristine '97 328.

Police found car yesterday, surprisingly intact.

Ordered new key from dealer today.

I was told that an e36 'remembers' up to seven keys. That is how it can have a rotating code yet work with multiple keys. It recognizes which key is inserted so it knows what revolving code to expect from that key.

The same guy told me that the dealer can log in to your computer and delete/block any of the keys so they will still open the doors but they won't start the car.

The parts man at the dealer in Washington DC says this is not possible. The car will always start with any key that it has ever used.

Has anyone had old keys blocked in the immobilizer of an e36?

Any suggestions on a shop in Washington DC who could do that for us?