I would dissagree with having 2 different species of anemones in the tank, its not a good idea.
Sebae's are known for being difficult to survive and care for. You could try pasting a pic of a clownfish hosting in the sebae to your aquarium to give them an idea of what you want. You have nothing to lose by trying. All you have to find is a pic of the same style of clownfish you have in a sebae.
They may host with it or they may never host with it, who can say when its the mind of a clownfish?
Thomas