The Resequence function is available from both the Action menu of the Group of Datums Members tab and from the edit tool palette.

If the Group is a 'Linear' group, pressing the Resequence button will cause the Group members to be Resequenced in increasing distance value from the Start of the Route in accordance with any Type Subclass rules defined for the member Datum Elements.

If the group being resequenced is circular, a dialog opens, allowing you to select the starting datum network layer element: