Thanks a lot,

I'm in a communication with the developers and see that they use asynchronous parallel calls of the above sp for merging data. It's another reason for the deadlocks,...

Too many deadlocks and timeouts?

and read commited snapshot is supposet to eliminate it

What can be done more?

namesnapshot_isolation_state_descis_read_committed_snapshot_on

F1SBON1

I suspect the SP called from .net is called with another isolation level (serializable or read commited)

in XE session i'm catching

xml_report < deadlock > < victim - list > <...