1) Child 2) Marriage acquisition 3) Member of a blended family 1) Stepdaughter 2) Stepson 
• (n.) A son or daughter of one`s wife or husband by a former marriage. • (n.) A bereaved child; one who has lost father or mother.
Step'child` noun [ Anglo-Saxon steópcild .] 1. A bereaved child; one who has lost father or mother. [ Obsolete] 2. A son or daughter of one's wife or husband by a former marriage. 
A child born to or legally adopted by your spouse before your marriage whom you have not legally adopted. If you adopt the child, your parent-child relationship is the same as if the child were biologically related to you.
[n] - a child of your spouse by a former marriage
noun a child of your spouse by a former marriage
A spouse
a child of one's husband or wife by a previous marriage. · any person, organization, affiliate, project, etc., that is not properly treated, supported, or appreciated: This agency is the stepchild when appropriations are handed out.