Viennese foundlings in Bohemia

I’m wondering if anyone has run into a Viennese “foundling” (basically orphan) in their research? I understand that these children were often placed around the empire in what amounts to a foster home. These caretakers were paid a stipend to raise the children til they were around 12. I’m trying to find out more about this arrangement – how much did they get paid? How would potential foster parents even find out about this? How did the infant get to Bohemia (did the family travel to Vienna?). I believe my great-grandmother was a foundling and placed with a family in Bohemia.

She is listed in the 1880 census as a Viennese foundling with a different surname that no one in the family has heard before. She was living with the person we always thought was her father and step-mother. It appears that is not the case now! I have ordered the Viennese orphan birth records through LDS but they haven’t arrived yet.

Thanks!