One of the new features in Family Tree Maker 2012 will help you see the relationship of children to parents at a glance. It’s called blended family view.
Blended family view is activated by clickinh a new button above the children list on the person view in FTM 2012. When on, the list of children includes all the children of the selected person, even those born of another partner. Watch this video to see Blended family view in two different scenarios.