Answer: They are unlikely from each other in the form of strangers
Step-by-step explanation:
According to the question, Alberto and Vivienne are not related with each other before the time of adoption.Hence, they have no biological link with each other even after adoption. Stephanie is biological child of Smiths but has no biological connection with Alberto and Vivienne from the time of birth.
Hence, all the three children are nowhere related to each other in term of biological factors as they are not born from same parents.They can be considered as random strangers.