The stepfamily has the same meaning as a family of origin with the added element of fate thrown into the mix, as a secondary family by marriage indicates a choice that brings with it a multitude of relationships.
If you have a stepfamily in your waking life, the people who make up that family represent character aspects of your personality and also reflect the primary relationship that connects that stepfamily to you. Such a dream may be reflecting both your own consciousness as well as the waking-life interactions of the individuals involved.
(See Also: Family Members.)
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