I would suggest adding the nem first as long as you can properly do so. The thinking behind this is, if you add the anemone fist it can get established in the tank. Once an anemone is established it can tolerate a lot more then one just being introduced to the tank. One issue with adding a nem second, is the clowns jumping right into it and roughing it up before it can even get it self comfy so to speak. If you went this method it would have to deal with being new to the tank and having some abusive residence all at the same time.