I'd agree with dcwcce: keep your miles together on NWA. It's too late in the year for you to try for status on CO anyway, so unless you have several more CO flights after this one in December or have many next year (that would bring your new OnePass acct up to reward levels), I'd consolidate. (And just in case you weren't aware, both CO and NWA have off-peak 20K-mile award tickets within the 48 states and Canada.)