When I apply the visitor visa for my parents, I didn't include all their syblings in the family composition form. Now it is time to apply for the immigrant visa, can I change to include all their syblings or keep the same as before? I prefer to including all but afraid they will check their previous record for the visa application. Any suggestions?

Another question: is it true I can apply their immigrant visa from Buffalo visa office since they stay with us more than one year as a visitor.( they are still in canada now).

Thank you very very much!