The imperative with multiple objects of pronouns

[Lynn]

why do you use the vous form of the verb when referring to us (nous) ?

For example, Voulez-vous des bonbons?

and the correct reply would be: Oui, donnez-nous-en, s'il vous plait.

Maybe I'm just confusing myself, but it really doesn't make sense, and I'd be happy to hear any explanations.  

[Thrissel]

Because "we" want them but "you" should give them (to "us").

The donnez is an "order": you give!
and followed by -nous you get you give to us!

[Lynn]

Thank you ever so much!