Maybe I'm misinterpreting your post... I didn't mean the individual letters, I meant the letter combinations. As in, you shouldn't start a local sorority called (say) Alpha Epsilon Phi, because there's already a national by that name, but no problem if you want to call yourselves (say) Epsilon Phi Alpha.
If you've found letters you like and that are meaningful to you, and there aren't any inter/national GLOs or locals/regionals near you that are using them, I say go for it.
