I am planning on a cake that will have a blueberry and lemon curd filling, but will be covered in fondant, if I use a store lemon curd will I still have to refrigerate? If I don't use lemon curd what else could I mix with the blueberry to have the lemon filling too? Also, the fondant layers should be in cake boxes if placed in refrigerator? Also, when stacking the cake layers what cake boards do most use? It will only be two layers, but each layer 4" , this is all new to me, and am learning!