Well, tbh I'd be concerned about you adding them. Weren't you just having troubles in the last several weeks? Sebae are very difficult anemone to keep.
I know we talked about the anemone your lfs
having being a sebae. There is no guarantee that the anemone will allow the hosting of the clown. This relationship can be helpful, but it can also be harmful if the clown is too rough.
You do NOT need to feed any photosynthetic anemones. If the clown does it if they form a bond, great.
Why would you want another anemone if you have one? The odds are still the same when it comes to forming such a relationship.
That said, I want to say that it is the larger maroon clowns that will pair up with sebae...is this what you got? If not, they aren't likely to even think about it.