I need help caring for children who are not biologically mine?

I am 26 years old and I started mentoring 2 absolutely amazing, young ladies (ages 12 & 14) 3 years ago. Recently, their parents up and left to California without them. The father is addicted to crack cocaine and the mother is addicted to the father. The children never had clothes that fit and the father would spend the food stamp money on crack. When they left they asked if they could give the children to me and sign me power of attorney for the children. My instincts and soul asked God what I should do and I felt if they had no other family who cared then I would take them and do the best I could financially. Little more about me I am a full time student going for my BS in Human Nutrition. I have a little less than 2 years left. I am recently engaged and we just purchased our first home together in a great school district for the girls. My fiance works full time and attends college part time for Criminal Justice. The frustrating part of the lovely situation is that the government does not want to ist us at all in raising and re socializing these young ladies. Their parents would receive all the help in the world and never even applied it to caring for their children. My fiance and I are completely capable of caring for ourselves but wow kids are expensive to care for, we do not have any children of our own. We love watching the girls play sports, helping them with their homework, doing crafts or baking, and just enjoy watching them be kids again. As the holidays approach I am sadden that I will not be able to provide them gifts under the tree. Winter is approaching and the girls have grown out of all their old winter clothes. If anyone has any advice for me. Maybe somewhere I could go to receive istance with clothes or Christmas gifts. Thank you for your time!