I have created a custom fieldset "Social Profile" in CiviCRM which contains one Yes/No field "Publish my profile" that is set to Yes (value 1) by default. If i edit the fieldset in one contact, i can see my default value is working fine.
Then, I have created a membership page that allow people to become new members. When they fill the form a new CiviCRM contact is created. The form doesn't contains the "Social Profile".
When a new member register, the information Publish my profile is not initialized. After verification, it seems that the custom fieldset is not initialized for the contact - no data in civicrm_value_xx for entity_id = <NEW_CONTACT_ID>
So my question : Is there a way to force initialization of the custom field set for a new contact ?