First create a tenancy as explained in add a tenancy initially specifying the name of a single, lead tenant.
Next, edit this tenancy as explained in edit a tenancy. To add an additional tenant to the tenancy click on the "[add additional tenant]" link in the Additional Tenants area of the Tenancies form. Note that the following fields must be supplied:
- Tenant (select a value from the drop down list)
- Title (select a value from the drop down list)
- First Name
When the tenant details have been supplied click on the "[add]" link.