Of course it isn't a "must" for a teknonym to be derived from the son's name. It ought to be derived from the name of the oldest child. However, you will find parents calling themselves "mother/father of Rana," but the moment they conceive a boy, they decide to be "mother/father of Ziyad." Sometimes parents decide to stick to the oldest daughter's name even after conceiving a boy, but friends and family insist on giving them teknonyms after the son's name. There are even parents who have only daughters and no sons, yet they invent a name of an "imaginary" son and use it. If anything, it shows the amount of unjustifiable misogyny existing in Arab societies. I think teknonyms should be abolished as they deprive a person of their own identity. Your name is the first thing that defines you. Call it a personal prejudice of mine. But I digress again. Feel free to have a kunya derived from your (future) daughter's name regardless.
