If your ticket is AA stock in a codeshare on CZ metal, you won’t be able to select seats on line and will have to follow the photocopy the passport route. If your ticket is CZ stock, you should be able to select seats on line, but there will be a cost for each seat unless you are a premium member of Sky Pearl. Using the 6 alpha/numeric code isn’t usually very helpful on CZ...they tend to respond better to the 13 digit ticket number. Good luck!