You have to set the Windchill preference to allow the checkout of the non-latest iteration. By default this is not allowed and probably requires your Windchill admin to set it so you can.
It is under Create and Edit but only available at the Site level. Even the wcadmin user cannot set it for their own account.
| Allow checkout of non-latest iterations |
Once you have it in your workspace a check-in will create the iteration above your current latest iteration.
Be sure to turn it off after doing the check-in!
