At the age of 15, me along with the majority of other dentists will recommend orthodontics. We usually say that veneers is an option for the over 18’s- when you are old enough to make the decision yourself as an adult, but all cases are different. As her teeth are not disformed or discoloured, but the position is wrong- then ortho is the first line of treatment. There ARE alternatives to the standard fixed braces- such as invisalign. Tese are invisable braces. I would advise a consultation at a cosmetic practice to discuss her options.