When a person is obligated to support both a son and a paternal grandfather, or a father and a son's son (grandson), what is the ruling on priority?

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There are two possible rulings. The first holds that the son and the father are prioritized because they are more closely related, connecting directly without an intermediary, and their inheritance rights are never nullified. The grandfather and the son's son do not hold this same status. The second possibility suggests parity (Taswiyah) between them because they are equal in terms of inheritance, agnatic association (Ta'ṣīb), and direct lineage.