Urgent-about parent air ticket

Dear all:

I am going to buy the air ticket today for next Tuesday\'s trip from BJ to NYC or NewArk.

I just heard that the visa office require that all passenager buy round trip tickets for a half year period.

If my parents plan to stay in USA for A YEAR to help me with my new baby, what should I do. it seems that you MUST buy round trip tickets per visa office.

any suggestions???

Thanks a lot for your prompt help