Multiple sales orders combine packing slip posting, print ssrs on screen, database deadlock

If it’s really about a deadlock (your didn’t tell us how you came to this conclusion), you should analyze the deadlock. Find which resources are locked, what are the lock types and which set of queries caused the deadlock. Let me remind you that a deadlock requires several queries - identifying just one of them isn’t sufficient.
You can find articles on internet about deadlock analysis, such as Understanding the graphical representation of the SQL Server Deadlock Graph.