Who is Cassi and Clio Gartos from Bounce and what is their importance?

Cassi and Clio are Eleni's twin daughters. They are 16. Ev calls them the sweater twins because the first argument she witnesses between the two girls is over a sweater. Ev shares a room with the twins, who always seem to be bickering over something. The twins also seems as if they are very helpful. They are always trying to help Ev pick out her outfits, give Mackey cream to clear up his acne and other small acts of kindness.