The name of 2 sets sibling actors that worked togather in Little House on the Prairie?

You're likely thinking of the Ingalls sisters:

* Melissa Gilbert played Laura Ingalls

* Lindsay Greenbush and Sidney Greenbush shared the role of Carrie Ingalls

It's important to note that Sidney and Lindsay were twins, so they were technically two sets of sibling actors, though they shared the role of Carrie.