Raising an orphan and being asked to give him his family name

Q 2: I have undertaken the responsibility of taking a male child from an orphanage to raise him. Before doing so, the orphanage, which is a governmental one, has asked me to give the child my family name without attributing him to myself. I have agreed to do so without giving him my name or the name of my wife. Am I mistaken?

A: You have done well by taking the child to bring him up, but it is impermissible for you to give him your family name. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.