I disabled default Joomla registration and only allow registration via logging in with Social Connect. I cannot work out how to default the value of a custom radio button field "show_on_members_list". The database field continues to show NULL after initial registration, which means the profile will only display on the members list once the member edits their profile.

Desired workflow:
- User logs in with Social Connect
- if user account does not exist, it is created with Default values (no visible registration page should be displayed)
- user profile should immediately show in the Members List
- user can edit profile and set radio button field "show_on_members_list" to "No".
- show_on_members_list should not be visible on profile
- show_on_members_list should only be accessible by profile owner (or backend admin) when editing profile

I have the field "show_on_members_list" as a Radio Button with:
- Default value = 1
- Options list =
1|Yes
2|No
- (played with combinations of Availability and Visibility settings with no luck)

I have menu of type Users List Table with:
- SQL Where = show_on_members_list = 1

Result after new user logging in with Social Connect:
- new users created with value show_on_members_list = NULL in database therefore not shown on Members List
- after editing profile, user can be displayed on profile (if choosing to)

Please advise how I can achieve the desired workflow. Thanks.