Thanks for all the replies. I have several CO flights coming so I'll do some experimenting and will follow up in this forum.

Just to make sure I was clear on what I'm trying to accomplish and for additional input this is it:

I fly enough miles to be Plat on one and silver/gold on another.

I wish to retain my NW Plat status. My preference is NW but NW doesn't cover south Texas very well and I have to rely on CO for those routes.

The main reason I want to obtain elite status with CO is that I check two 69.5 lbs. bags and pay $25 for each bag, each way on CO. Obtaining elite status gives me 70 lbs. and will save me $100 per trip.

Even when I achieve silver/gold on CO and satisfy the above I will still losing out on my EUA Plat opportunities unless there's away around it.

I've tried several times to get my Plat status honored on CO for the sake of saving the overweight fee but have failed.

Right now I have a return trip coming up under Plat status but I see no way on the website that I can change FF# myself. OLCI may be a different story.