I will study in Canada next month and get S-1 (student) visa while my familly get V-1 (visitor) visa to accompany me, all visas have 4 years validity (2007-2011). The problem came after I plan to purchase an air ticket, the travel agent ask me to buy return ticket for my family consider that they hold visitor visa, some arguing that I can use single trip ticket because the validation duration is 4 years.
I'm really appreciate should you got any info to share

warm regards,

Erlangga