Master-detail content type. How to?

Hello. I need to create a content type with a master-detail structure.
The form, for add content, may look like:

Full Name :
[______________________]
some others fields ....

Friends: [Add friend] <-- to add details (friends)
[______________________] [______] (*)Male ( )Female
[______________________] [______] (*)Male ( )Female
[______________________] [______] (*)Male ( )Female

[Send] <-- main and only one submit button for the content type

How could I do It? I have search but nothing found.
Thanks.