If we both are married to different people n have a newborn together.can he give the baby the biological fathers name

Yes and no. You will not be able to do so at birth. As a married woman, your child is legally a child of the marriage. As part of a divorce you can provide proof (dna) that husband is not the father, and the Divorce court can order that child not to be of the marriage Then you can ask the juvenile court for a parentage order showing bio dad as father. When you have