Yes, lookingforadvise, you may find yourself paying child support regardless of the bio father paying support. In legal terms it is called Loco Parentis. I believe the courts look at it from the view that if the children have benefited financially from your income i.e. food, shelter, clothing etc. you will be obligated to continue to support them.
I found this article for you:
http://www.edmontonsun.com/News/Colu...0/1347511.html