As you mentioned that your wife is not having any kind of pain there is no need of any medications, why to create unnecessary side effects.
Next Steps
She has to go with neck, shoulder and back strengthening exercises as this exercises would help her to correct the posture by strengthening the muscles and supporting the internal structures. She can go with shoulder and back mobility exercises to avoid stiffness. When she feels some stiffness at the shoulder and back she can go with hot formentation for 15 minutes at least thrice in a day.
Health Tips
Continue using the brace as it will also help to improve her posture