I really don't know you or a lot about hamsters really BUT I remember you posting before. You really didn't listen to any of the advice did you..? And how long is it since you last cleaned out your hams if you have only just noticed a baby wandering around with its eyes open? And yes please split up Mum and Dad now as I think its only a very short time after birthing before they are ready to mate again. Also one is a very small litter and Mum or Dad may have killed the others in order to cope...but of course check, although you would probably have seen others. They normally wander out of the nest before their eyes are open, once they have opened their eyes you can carefully clean the nest.
I'm sure someone else with more knowledge and experience will offer some advice for the sake of these poor hamsters of yours.
