When should the Spouses and children of H1B1 visa applicants, who are not Singaporean, apply for a derivative visa?

Spouses and children of H visa applicants who are not Singaporean are strongly encouraged to apply for their visas at the same time as the principal applicant, regardless of whether they have firm plans to travel to the United States. If the H1B1 visa holder is not present for the application of their non-Singaporean spouse and children, the applicants may be asked to apply in their home country, where their marriage and birth documents can be properly verified.