If the birth mother has no other son, the adopted son may have to perform the rites. Dharma Shastra specifies who has the right to perform rites to be performed on the first in a specific order. If the birth mother does not have any son or grandson, then the duty of final rites can be performed by the adopted son, but he does not have the prime authority; he only has a secondary authority; it can be advised on who can perform the rites only after consulting the order of priority.