To delegate marking of anonymous assignments you can use Trunitin Assignment by Groups
First, you have to set up blackboard group of all the students assigned to each marker, see Blackboard Groups If groups are being created just for delegated marking then names the groups after the makers.
You setup the Turnitin assignments as a normal anonymous assignment.
When you come to mark the papers instead of clicking on Turnitin Assignment under module tools click on Trunitin Assignment by Groups
Then pick the assignment
Choose the group of student assigned to you from the drop down list
Then click on the paper title from the anonymised list to start marking
and mark as normal.