First, the children are considered wards of the state so any child support would be sent to the state for reimbursement. You would/should get a monthly stipend from the state for being the foster parent. You may also get food stamps and the children would be on medicaid. If they are young enough to need childcare while you are in school the state would/should pay for that as well. (Each state is different on how they implement the federal guideline.) One thing I did not see mentioned (and I apologize if it was and I missed it), but how close are you with these children? Have you been in their lives? Not to sound heartless, but if you were not a part of their lives up to this point, then the only advantage of you being the foster parent is keeping the children in the family. This may even cause more angst and issues for the kids than an outside foster home. With you as the foster parent, your family will feel they have more pull and say in what happens with the kids and may interfere more with Social Services. They may pressure you to allow your sister access when Social Services is requiring supervised visitation and classes/treatment for the parents. Things to think about.