I have memberships 2 pro installed and imported members

Hi
I have memberships 2 pro installed and imported members across from the original memberships plugin. But I now have a csv of people we are giving a complimentary membership. So I need to import and assign to a specific group. I have tried to use the import tool in Memberships 2 but it seems this may be created to deal with exports created in memberships, not a csv or xls etc.

Is there a tool or script that will import such a csv, and ideally allocate to a group, or if I need to write a script to import, is it a case of just creating users (ie using the default wp import in tools or writing a script), and then binding the new user id and the specific member group id relationship somewhere?
Thanks
Mike