GSW: Joseph had no paternal claim. It is like the case of Boaz and Ruth. Obed is actually the child of Ruth’s late husband. Not Boaz. Boaz was the one that slept with her but that first child belong to Naomi’s dead child that married Ruth. Is this understood?
The same principle applies to Mary and Joseph. Even though Joseph is her husband. Her first child was for God. Joseph cannot claim paternal right. He can also have the woman but not via an official marriage. The way Boaz didn’t have an official marriage with Ruth. She was a redeemed wife already married into the family she does not need to do a second wedding.