Hi

I would suggest that you try this scenario.

Create a smartobject from sharepoint (Click on site actions > K2 site settings > K2 smartobject site lists and libraries > Tick your lists name > Click create) and then by using the Smartobject Service Tester Tool publish that smartobject to K2 Designer and generate or create views and forms from the published smartobject.  This will enable you to be able to add, edit, save (Update) and delete records from either sharepoint list or from K2 Designer.

Kind Regards