Your RBTA is really too small to host one clown much less two. I think in time (as the nem gets larger) that there will be enough room for them both to be in the anemone. I think the first step toward them pairing has already occured ie: the one with the best hangout (anemone in this case) will become the female.
Ocellaris are about as easy as it comes regarding pairing. It's a bonus that they're already aware that the BTA is a host. BTAs are a tough sell for ocellaris generally speaking.