Her 3 year-old son just got extension on tourist visa this month so will be valid till 15th April (but they will fly out to Japan on 7th April and come back).
Does her baby need to get another extension before traveling?
Not sure if it can be done.
For herself, she is going to apply for Non-Immigrant Type O as a parent taking care of her eldest son (12 year old) who is studying here so should be no problem.