Jess didn't know Anna was planning to adopt her. The possibility of adopting adults who have undergone age regression was the aftermath of the existence of Gen-Tech products on the market which enable this. Many adults who have undergone such adoption have done so on purpose to be adopted later, by their friends, or simply sold themselfs as babies to completely alien families.
The only advantage of this situation was that the person subjected to AAAR (Adoption After Age Regression), and having the mind of an adult, enjoyed most of the rights of an adult, exceptions were that:
1. They could not work until their new form reached the age of 8, when they had regained sufficient psychomotor coordination.
2. Students could not choose a new school themselves, but they could not be removed from the school list in which they were enrolled before the regression without their consent. (Not applicable to sports and mechanical students.)
3. In the case of studies where psychomotor coordination was needed, e.g. to mix chemicals, they need a caretaker who will do it for them.
That's what Jess was supposed to be subjected to.
4. Finance, ownership and real estate affairs of such a person were dealt with by a person designated by the court.
Anna recently recovered from depression after stillbirth, so looking after Jess gave her a sense of accomplishment, and in the meantime she was gathering evidence that she was the perfect mother for AAAR adoption.
The official who reviewed the evidence issued a positive verdict and Jess became Jessica Freeman, the adopted daughter of Anna Freeman.