Since you are not married, in tx he has to sign and notorize paperwork that states that he knows he's the father, otherwise he can not be put on the bc.
This is what my dh had to do before we got married.
When you get a dna test done his name can be added though.
I also have a 9.5 yrold son, his bio wanted nothing to do with him. I chose to not file for cs, or try to put him on ds's bc. He has never tried to contact my son.