I didn't see you already reply,
I just edited my previous message as it seems I'm having problems with additional fields in hikashop registration in any case, i must have messed something so now i'm testing.
I understand the best solution now is to use simplified Children registration and then capture extra fields in moodle.
I wrote to Hikashop developers to, in order to see if they are able to modify the register view to allow multiple registration so that could be used by Joomdle.
Thank you very very much for your support.
Hope this can be helpful for other people to
Paolo
EDIT: The issue wasn't actually an issue, it's just because in Moodle all the extra fields from the registration in Hikashop get automatically filled only when the user pays and get enrolled in a course.
