Taking on the responsibilities of a stepparent and adopting the traditional role of mother or father, often does not work very well.
The primary challenge for a stepparent is to develop your own unique role that works both for you and the family.
This will also depend on the ages and personalities of the children in your stepfamily and the time you get to spend together. What is absolutely essential is that you and your partner role model a loving, respectful and emotionally secure relationship for the children.
Couples need to make time for their relationship and have couple-time on a regular basis. Yes, this can be difficult but this helps build stronger bonds as a couple, as a family and also benefits the children. Along with patience and open communication this will help build a successful stepfamily.