What are the conditions for establishing lineage through self-acknowledgment (Iqrar)?

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If one acknowledges a child belonging to oneself alone, four conditions must be met for the lineage to be established. First, the acknowledged person must have an unknown lineage. Acknowledgment is invalid if the person's lineage is already known, as this severs an established lineage. Second, no claimant must contest the lineage. If there is a dispute, mutual nullification occurs, and favoring one claimant over the other is unjustified. Third, the acknowledgment must be plausible, meaning the acknowledged person could possibly have been fathered by the acknowledging person. Fourth, the acknowledged person must be someone incapable of speech, such as a minor or an insane person, or the acknowledging person must confirm the lineage if the acknowledged person is capable of speech (a mature person). If the capable person later denies the lineage upon reaching maturity, the denial is not accepted because the lineage has already been established. The father cannot be subject to an oath regarding this established lineage, just as if the father were to later deny the established lineage, his denial would not be accepted.