Pass Values

I have a link www.example.com/survey.asp?usr=[username]&pwd=[password]

survey.asp is going to be a redirection that redirects to one of these random links;
www.example.com/survey1.asp?usr=[username]&pwd=[password]
www.example.com/survey2.asp?usr=[username]&pwd=[password]
www.example.com/survey3.asp?usr=[username]&pwd=[password]
www.example.com/survey4.asp?usr=[username]&pwd=[password]

I need to pass what ever is in the [username] and in the [password] fields too.As the [username] and [password] would be unique for each url (as I will be emailing 1000's out which will be email-merged)

for example if the original url is; www.example.com/survey.asp?usr=abcd&pwd=1234 then it may redirect to: www.example.com/survey1.asp?usr=abcd&pwd=1234