Thank you for reaching out to the wefugees community.
It's not necessary, that your child has your family name
Since you have the acknowledgment of paternity and joint custody, you are recognized as a father, even with another family name.
I hope my answers were helpful and I would be very happy if you would contact me again with further questions. I'm a consultant with mbeon and I‘ll be glad to help you over a longer period of time. Mbeon is an online advice for migrants via the mbeon app, which you can install on your smartphone for free. Download it from App Store or Google Play Store. You can find me in the mbeon app and get confidential individual advice in a secure virtual space without other people reading our conversation. Further information: www.mbeon.de.
your mbeon advisor