Thank you for your response and new question.
Even if the sister would testify that he was going to change his will and include you, unfortunately, CA law really is not favorable because you were not married and you were not registered domestic partners and there is no written will because he never changed it. Thus, you would need to rely on the courtesy of the sister here and you need to play on her sympathy now while she is saying he wanted to make provisions for you, but he never got around to doing so.
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