Can I solicit some of your opinions?

My partner is currently married but separated with his wife, not on papers though. They had some personal issues way back then and don't want the idea of getting back together. Then I came into the picture and we're having a baby in a few more weeks. Moreover, my partner and I would love to use his family name for our baby soon. I know our relationship is against the law under Family Code. But I would really appreciate your thoughtful opinion regarding my situation. PS. I just got my PRC license last year.