What should we do regarding a cousin born to a non-Muslim Russian woman in Kazakhstan, given his desire to connect with relatives, and is it permissible to consider him among the kin?

If the child is a product of adultery, he is not attributed to the questioner's uncle. However, if the marriage was valid or invalid with the belief in its validity, then the child is attributed to the uncle and is considered a Muslim as long as one of his parents is Muslim. The non-Muslim mother has no right to his custody if he is at the age of custody; rather, custody belongs to the qualified Muslim paternal grandmother. The child and his mother must be introduced to Islam.