What should I do with a young man who deceived me and married my daughter informally ( عرفيًا ) and impregnated her, and is it permissible for me to place the newborn in an orphanage for fear of scandal?

If the young man's marriage to your daughter was without a guardian (wali) or witnesses, then it is an invalid marriage according to the more preponderant opinion. However, it is a marriage of شبهة (doubt/ شبهة contract) where the child is attributed to his father, and the father is responsible for his care and support. Therefore, it is not permissible for you to take the child and place him in an orphanage.

However, if it was merely an agreement between them for cohabitation without marriage, then the newborn is not attributed to the fornicator but to his mother, and she is responsible for him. Placing the child in an orphanage is not permissible if it will expose him to harm, such as not knowing his relatives.

The young man committed a mistake and deserves disciplinary punishment (ta'zir) from the authorities, and it is not permissible for you to assault him. Your daughter erred by enabling him to be with her.

We advise marrying the young man to the girl if he is religiously acceptable, especially if she has become attached to him. If what happened was fornication (zina), then it is not permissible to marry her to him except after she gives birth and both of them have repented.