All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The boy and girl whom you adopted do not inherit anything from your wealth, and adopting them under your name is something forbidden. We have already issued Fataawa 84422 and 82371 clarifying that adoption is forbidden in Islam and that the adopted person has no right in the inheritance of the person who adopted him. However, it is permissible to gift him/her something or make a will for him/her.

Moreover, you should know, dear brother, that the boy whom you adopted is a non-Mahram to your wife and it is not permissible for him to stay in seclusion with her or to shake hands with her. He is also a non-Mahram to your niece [daughter of your brother]; this is of course if there is no reason which renders him a Mahram in both cases.

As regards how your inheritance should be divided, then whoever dies and leaves behind a wife, two brothers and a sister, all of whom are full brothers and full sister, or all of them are from the father’s side only, and he did not leave any other heir, then his wife gets a fourth of the inheritance and the remaining should be divided between his two brothers and his sister, the male twice the share of the female.

Furthermore, now you should not preoccupy yourself about how your inheritance will be divided after your death, because it might be that the situation would change and one of the heirs would die before you or that you will have another heir born to you. What is important is that you should endeavour to correct the mistake which you made, and change the family lineage of the children whom you adopted in official papers by naming them after their fathers.

Allaah Knows best.