I'd trickle charge it. Jump starting can definitely damage BMW's. The problem is the alternator is pretty meaty, like 170A, and electronically controlled.
For the car being started the problem occurs when you disconnect the jump leads. The load on the alternator suddenly increases massively. The voltage can spike to perhaps 18V or more, just for a moment. It depends what other consumers are on to absorb the spike. There are loads of electronic modules on these cars and some just aren't as robust as they should be. On BMW's the MULF (Bluetooth module) and glow plug controller module tend to instantly die....
You face the exact same problem if you are the car doing the jump starting - possibly worse. Here when the leads are disconnected the load on the the supplying car is suddenly a lot less than it was and the voltage spikes.