How many children did the Ingalls have altogether in their home during the run of 'Little House on the Prairie?'

Charles and Caroline Ingalls had four daughters, Laura Ingalls, Mary Ingalls, Carrie Ingalls and Grace Ingalls.
They adopted a son Albert Quinn Ingalls.
Later in the series they took in two other children James Cooper Ingalls and
Cassandra Cooper Ingalls for a total of seven.
http://imdb.com/Title?0071759

I believe one or more of their grandchildren may have stayed with them at one time or another, but you will have to check the episode guide.
http://www.timvp.com/lilhouse.html

They also had a son for short time before he died. Charles Jr? They called him "Baby Freddy."
total of 8