The niece is the unnamed daughter of the inspector's sister, who is arrested on day 21 for an unknown reason. It is possible to adopt the niece on that date, but it will cost 40 credits. She will be added to the number of family members the inspector has to care for, but the day after she is adopted, she will bring her mother's savings with her, which will add 100 credits to the inspector's available cash.
Netting an immediate profit of 60 credits, but increasing the food costs for the family by 5 per day, she will yield a profit of 15 credits if kept alive until the end of story mode. However, if fleeing the country (endings 16 and 18), she will end up costing money through the need for an Obristani passport of her own. Getting her a forged passport will cost 25 credits, and, depending on the number of citations the inspector has received, confiscating one may cost even more.