"Although, historically, stepfamilies are built through the institution of marriage, and are legally recognized, it is currently unclear if a stepfamily can be both established and recognized by less formal arrangements, such as when a man or woman with children cohabits with another man or woman outside of marriage. This relationship is becoming more common in all Western countries. Many divorced parents, often with children, re-couple with new partners outside of traditional marriage.

Historically and to this day, there appear to be many cultures in which these families are recognized socially, as de facto families. However in modern western culture it is often unclear as what, if any, social status and protection they enjoy in law.

The stepparent is a "legal stranger" in most of the US and has no legal right to the minor child no matter how involved in the child's life they are. The biological parents (and, where applicable, adoptive parents) hold that privilege and responsibility. So if the biological parent doesn't give up his or her parental rights and custodial to the child, a parent's subsequent marriage cannot create a stepparent relationship without the parent written consent before a "child" reaches adulthood. In most cases, the stepparent can not be ordered to pay child support.

Still it is not at all clear what formal parenting roles, rights, responsibilities and social etiquette, should exist between "stepparents" and their "stepchildren". This often leaves the parents in unexpected conflicts with each other, their former spouses and the children.

For all the confusion which stepparents may feel, it is often even less clear to the stepchildren what the interpersonal relationships are, or should be between themselves and their stepsiblings; between themselves and their stepparent; and even between themselves and their birth parents.

These relationships can be extremely complex, especially in circumstances where each "step spouse" may bring children of their own to the home or in households where children are expected to actively participate in each of the newly created families of both birth parents.

Although most stepfamilies can agree on what they do not want to be for one another, they are often hard pressed to agree upon what they do want to be for one another. This makes it difficult for everyone in the family to learn their roles. It is especially difficult for the children, because the roles and expectations of them change as they move between the homes and families of both of their birth parents."

Exert taken from Wkipedia....however the step father in these movies would pay little attention to his 'rights' as a step father!!!