Hello, I have twins a boy and a girl. They are now 9m old . They are now trying to sit. They born in 6m 25days of pregnancy.birth weight was 1.2 kg. Physiotherapist suggested some exercise as they are late in activity in compare to 9m born child.what activity should I expect from the babies. One baby had rop stage 5 and underwent surgery in 3m and 4m.