that runaway and end up on the brady's lounge
chairs in their backyard? I remember Dwayne
and Steve but I can't remember the 3rd.
I know they referred to themselves as the
3 musketeers and Ken Berry played their
adoptive Dad to be. Well I know one of the kids was his biological son, but the other 2
were not. Please Help it's driving me nuts.

That episode is called Kelly's Kids. Ken and Kathy Kelly decide to adopt one boy, Matt and end up adopting three, Matt and his two friends, Dwayne and Steve.

"Matt" was actually portrayed by Bobby's(Mike Lookinland) brother Todd Lookinland.