I'm 19 and am neither a stepmother nor a mother. I just registered because I needed some advice and ended up reading some posts that I really needed to comment on.
A lot of women were complaining that the 11/12/whatever-year-old stepdaughters would sit on their father's laps or show too much physical affection.
Some complained that they felt their husbands were giving the daughters too much attention and there wasn't much left for them.