It takes time, or in my case, a clown that was already hosting showed the new guy what to do lol. My first clown (standard ocellaris) associated with my Xenia, and kept my second clown (black and white ocellaris) away from said Xenia. When I split the pair up and put the black and white into cube with two rbta, he went to them within days. He then showedy new lg black ice that the nems are home. When I got my phantom, I moved the black and white out and the black ice showed the new phantom the nems.
A true case of monkey see monkey do.
On another note, when I got my new Wyoming whites, the dominate one took to the Xenia as well, and when I introduced a rbta, she was in it within two days.