Yeah, I let littermates run loose like that about two years ago. Didn't work out too well for me and these were dogs that never had a tooth in them(until I let them loose). Tried it with mother and daughter also and worked well for a while until one day the mother was excited to see me and did a vertical leap in the air and when she came down she just barely nudged the daughter which caused a full blown fight. She apparently didn't like her mother pushing her around anymore and it wasn't good having a grown bitch on my 11 month old pup like that. Never thought about doing it again because the dog was too valuable to me to wreck.