I have question RE fiberglass repair.

I'm having trouble reparing fiberglass damage to my strip built Greak Auk. After a year of use the fiberglass under the epoxy on the stern and bow stems has turned white in a few places where minor impacts have occured. The damage appears to be only cosmetic, but I would like to repair the damage nonetheless. I've tried cutting out the white damaged areas and putting in new fiberglass and epoxy but the edges around the area that I've cut out end up visible as white score lines. As I write this I'm thinking that maybe I could gently sand these score lines out of the epoxy? If anyone has any input it would be greatly appreciated.