Is it Islamically permissible for a man to marry his paternal uncle's daughter who is afflicted by demonic possession, and will her condition affect the marriage and the children, and can she be treated according to the Prophetic Sunnah?

The possession of a human by a jinn is affirmed by the Qur’an, the Sunnah, and the consensus of scholars. This does not preclude marriage, but the other party must be informed because epilepsy (or possession, as understood in this context) is among the defects that establish the option of annulment. This could affect the marriage if the husband is not patient, and the devil’s influence depends on the strength of one's faith. This affliction is a trial for which the patient will be rewarded with the greatest reward. It can be treated by reciting the Qur’an and lawful supplications. It is advisable to be deliberate in the decision to marry. If it is highly probable that one can be patient and endure the condition, along with the girl's satisfaction in terms of religious commitment and character, then one should put trust in Allah and proceed. However, if one knows they cannot be patient, there is no need to embark on the marriage.