We have no biological children and are raising an adopted child. How do we make sure he is not left out when we are gone?

An adopted child does not inherit through faraid, so his future depends on your planning while you are alive. There are two main channels. First, a gift (hibah) while you are healthy, for example a house or savings, fully handed over and documented. Second, a will (wasiat) of up to one third of your estate, which does not need the heirs' consent because an adopted child is not an heir. You can also name him as a takaful beneficiary. Without these steps, your property will go to your siblings or other relatives, and the child you raised may receive nothing. Be upfront with the wider family about your wishes so they respect them later. See adopted children and inheritance.