My question involves adoption law for the State of: Texas

My husband and I are in the process of seeking info regarding terminating thet rights of my sons biological father whom he does not know and who he has only seen once at the DNA office when he was 1 my son is now 9. I want to terminate the rights of the biological father and my husband will step in as the father like he has done for the last 9 years of my sons life. I met my husband when my son was only 6 months. but in the state of texas i was told I need the consent of the Biological dad even of he does not play a role in my sons life. Also my son had my maiden last name, so he doesn't even have a part of the sperm donors last name. why do I need consent from him. and I am more than certain a judge will rule in my favor. his bio dad has done nothing but gave a few $ here and there and according to Child Support he owes me 26,000 but I don't even want it. I want my child to have my husbands last name and to have his name put on the birthcertificate cause he been a real dad. Any legal advice out there?