A vietnamese company needs at least one legal representative officer.
After the company registration is completed, the legal representative officer needs to be a resident in Vietnam. If he/she cannot stay in Vietnam (he or she goes outside Vietnam over 30 days), he/she can authorize another person to sign on the documents – such as contracts, tax reports, etc, – of the company by issuing an authorization letter.
However, you shall carefully discuss this matter with your agency.
Also, a Limited or Joint Stock company can register two legal representative officers or more.