The damsels have been in the tank for between a week and 10 days.
I take it you used them to cycle. If thats the case, I would wait a week or so to be sure your cycle is complete. Thats a little fast.
If you buy clowns as babies, they may not sucessfully mate, but they should pair up. One will grow larger than the other and become the dominant female.
Mating of clowns is possible, but special procedures need to be taken. Sorry, I am not familiar with those procedures.
Also clowns do not need a "host" to thrive, they can do very well without one.