Dawn Lyn mentions in a recent interview with "On Screen & Beyond" (episode #419) that she, and her brother Leif Garrett, auditioned as Brady Kids. Unfortunately this brown haired girl, and blonde boy did not fit the bill. She doesn't elaborate on this, but its a great interview you can hear on the link above. (Brady Talk is at the 17:00 minute mark). Brown haired Debi Storm has also spoken about the fact that she was up for a role as a Brady. An Interview With Debi Storm
Dawn Lyn in"My Three Sons"
Leif Garrett in "Nanny & The Professor"
Debi Storm in "Family Affair"
Debi Storm as Molly Webber in the "My Fair Opponent"