Yes, please. While you've given some nice examples of preteens and teenagers, you have yet to show where the consent of a seven-year-old child is, as you stated, "required" for the adoption to be done.
To the OP: yes, you can get an answer. You don't want the biological father held accountable, want the stepfather to pay child support but not have any legal rights to the child, and allow a third man to adopt said child. What you're asking is impossible and ridiculous.