My corp travel agency requires that i book continental codeshares vs "direct" united tickets because we get discounts with continental. so this week i have a flight from iah to denver with continental flight # and co operated outbound and continental flight # and united operated return. Neither have been upgraded yet. I am plat on co and prem ex on united (from the match). what's the best way to maximize upgrades? i assume i can't put the different ff #s with the different segments can I?