Will the state help us with our foster kids’ medical needs?

My husband and I have two foster boys, ages 4 and 7. They are siblings and came from a terrible environment. Both are on the autism spectrum and have some other emotional and medical needs that may be lifelong. The Las Vegas foster care agency we’ve been working with is pushing us to adopt, but we aren’t sure we could meet all of their expenses if our foster care stipend was cut off. We asked several of the social workers about financial assistance after an adoption goes through but they said we need to talk to a lawyer about negotiating it. Does the foster care agency give financial help to adoptive parents if the children have ongoing medical costs?