I met with a couple today who reminded me of the importance of at least doing a basic will for blended families. The father wanted to make sure his step-children were treated as though born naturally of him. This would not happen under intestate laws (laws governing how stuff is divided absent a will). He wanted his estate to reflect his heart towards his children. So, I was able to do a basic will for him to make sure that happened.
If you have a blended family be sure to talk to a lawyer who understands these issues to make sure your family is protected the way you want if you were to pass away.