Legal Question in Real Estate Law in California

In California, your father would execute a quitclaim deed to transfer his interest in the property to his daughter.

Mr. Cohen may have provided the answer. However, your question might mean either of two things:

(1) Your father and your sister bought a house as co-owners, and now your father wants to transfer his half interest to your sister, his co-owner. That's what Mr. Cohen's answer covers.

(2) The people you refer to as your sibling and your sister are not the same person. Your father is attempting to transfer not just his share, but also sibling's share, to sister. This he cannot do without sibling's participation. A co-owner can transfer his share, but not the other co-owner's share.