t3eachRLADY has good things to say re the possibility that you may be put off by your stepdaughter's potential career choice. Here is another perspective for you to consider.
You say your stepdaughter is coming home from a school for high risk children.
You do not say how old she is, but from the intent to go to college, and your reference to your wife having "raised her alone," I am guessing that she is somewhere in older adolescence. The fact that she has been in this type of placement indicates the likelihood of emotional/ psychological/ or possibly behavioral issues.
My strong suggestion is to work with the school your stepchild is coming from to identify and help you put in place supports for both your daughter and the family once she is residing at home.
If she is going into the public school system before going to college, your stepdaughter may qualify for special education supports in school, as she may possibly be considered as having an emotional disability. (This would have to be determined by psychological testing, which may already have been done if she is in a high risk school.)
If she is actually going to be living with you while she goes to school, as you say she intends to,you might also want to consider some outside behavioral counseling to help your stepdaughter adjust to life back in your home, and to help the family adjust as well.
Whatever the situation, if she is in your home, you have a right to set ground rules and house rules, and expect her to follow them. Be firm, fair and follow through with consequences, if your requirements are not met. Structure is very important for all children, young or old, including those who are chronologically, but not yet emotionally young adults. Limit setting is an anecdote to being taken advantage of. All kids, even older ones, need predictable limits.
You and your wife will be best off to agree on what the limits and consequences are. If you cannot agree, try some private counseling with a social worker or family therapist who can help you negotiate this very important matter. Sometimes a trained social worker can help the entire family to navigate the difficult situation of an older child living with parents.
I wish you luck. Let us know how it goes.
Bette J. Freedson, LICSW, LCSW, CGP
Clinical Social Worker
JustAsk Expert
http://www.singlemomsos.com/index.html