I have a question about wills

My husband and I are having Wills done for ourselves. We have 3 children, one I had when I was 18 with a boyfriend. When he was 6 months old we established custody, I was given primary custody and the father joint legal. Fast forward to now, my son and his bio father don’t have a relationship nor know each other. Haven’t spoken in years, and when they spoke years ago, it had been years before that when they spoke last. Finally, my question is, in my Will I have my children going to a family member. Would there ever be an issue with my oldest child being separated and placed with his estranged biological father? Given the Will, and my son would be able to speak for himself (he’s 15 now) that he doesn’t know his biological father? I’m sure I could ask this at our Will appointment but just seeing if anyone knows or has witnessed this with any other family.