Adolescent attachment theory has not received as much attention and research as infant attachment theory. Many attachment theorists believe attachment extends into adolescence and adulthood. The purpose of adult attachment is to keep adults in contact with potentially helpful peers.
Younger children have an easier time transitioning into a stepfamily than teenagers do. Although most adolescent relationships with stepparents are positive, they are more distant because the adolescent feels closer to their biological parents. Oftentimes adolescents will become depressed, withdrawn, and antisocial because they are struggling with adjusting to the new stepfamily.
I do agree with the article that more research should be done on adolescent attachment, mainly because this is such an important time in development. This is the period when a child begins to develop into an adult, and there are so many physical and emotional changes going on that will affect the adolescent for the rest of his or her life. And I think is it important for adolescents to be securely attached to their parents during this time because secure attachments lead to healthy adult relationships later in life. Thus, it's also important that stepparents are aware of how big of an impact this change is on an adolescent and do their best to be understanding and try to form a secure attachment with their stepchildren.