Answer:
A family systems therapist might say that Mia and Isabel's relationship was enmeshed.
Explanation:
An enmeshed relationship occurs when boundaries between the individuals involved are not clear. An enmeshed parent only looks out for his/her child, meaning the child is the only focus the parent has. This often leads to a lack of self care for the parent.
In this case, we can see Mia and Isabel's relationship is enmeshed since there are no boundaries; Mia never leaves Isabel alone, even in the classroom. Mia's whole life is Isabel.