Scenario: Diagram saved in the database and i need to update the unique id of the Shape ports with the database values.

code snippet:
int portCount = shapeAdded.Ports.ChildrenCount(null);
for (int index = 0; index < portCount; index++)
{
NPort shapePort = shapeAdded.Ports.Children(null)[index] as NPort;

//assigning simobject unique id to nevron as if nevron port unique id
//is changed, connectors will be detached from the shape and can never be
//connected
shapePort.UniqueId = new Guid(portNode.SimUniqueID);
}

Assign the ID from the database to the Id property of the shapes, not to the UniqueId one.

Best Regards,
Nevron Support Team