The information can be found in the tutorial below.

http://convio.adobeconnect.com/tr_returning_teams/

Steps.

1.  First you would need to edit the teamraiser.
2.  Next Click on Identify Teamraiser and on step 7 previous event association choose an event.
3.  Next Go to step 3 select event options and click Edit Advanced Options and choose C. Define returning Team options.
4.  Check the Returning Teams allowed box.
5.  Move down to Returning Team Captain Role and Choose to Only Allow the previous Captain.