1. Is the "Title" field set as "Summary field" in the content type, it is required when it want to be used as userkey.
2. The userkey is a primary key, it can not be changed when the title was changed. But the user can edit it manually, you just need to create a field named "UserKey" in the content type.
Regards,
Jifeng Huang
Kooboo Team
Microsoft ASP.NET MVP