I really dislike
Cody and
Jackson, although they do go together. But I don't think
Erik or
Scarlett go well with them, nor with each other.
Cody and
Jackson are all modern and trendy and cowboyish, and
Scarlett is elegant, and
Erik is historical and Scandinavian. I'm boy no means an advocate for matchy names on multiples or siblings at all, but I do think that siblings should have names that match in style.