i wouldnt because the general rule of thumb for clowns is 1 - 2 per tank. if they host something , weather or not its an anenome, or mushrooms, or a powerhead, they have something to protect and will get meaner than when just 'free-swimming' If 2 of them pair up , which hopefully their is somewhat of a size difference so dominance is established quickly, then the other one will possibly be hunted down.
my brother has in his 135, the exact trio you are talking about, and it so far they are ok, but that is a big tank, and they are all free swimmers for now. so it is a risk. i would get rid of one of the regular ones and get a B+W one that is significantly larger or smaller than the one you keep.