I always knew we would have Kelly's Bird Rights (obviously), but wasn't totally sure about JJ's. This from CBAFAQ:
The first season of the three-year tenure doesn't have to be a full season. If a player signs midseason in year one, then plays for two additional full seasons, his team will have full Bird rights following the third season.
We had JJ for a very limited time in his first season and he has since played two seasons for us. I was always under the assumption that he was automatically gone if we signed a big name FA, but evidently we could drop KO and keep him if Ainge so chose to do so.
Either way, I don't see us keeping both of them - mainly because I have very [naive] high hopes for free agency. I guess it all depends on the player or players we bring in.
Edit: I realize we signed JJ using his Bird Rights in the first place since we acquired them from Detroit, but wasn't sure they transferred to the next contract with the 3-year rule.