Visitor Visa for Sister and Brother

[b123]

My family applied for a visitor visa including my brother and sister. My parents visa got approved and they rejected my brother and sister visa and gave 214(b).My sister is working and brother is studying.

Please advise what additional paperwork should be them for re-applying?
When should we apply the visa again

[immihelp]

Read https://www.immihelp.com/us-visitor-...young-persons/