This is a little off topic, However I have my 1st CO codeshare on a NWA ticket. I received my EUA's on the NW legs last night for LAN-DTW-IAH, but the CO leg IAH-AUS has not come through. Does this happen automatically, and can I change the seats, once assigned, in the NW website or do I need to contact an agent?

I might be a bit early as I am 5 days out and CO may not have run the EUA yet, but your opinions are always appreciated.