So a CA can't bid to an FO spot. All pilots with 950 will be displaced to CA spot. NO pilot should preference to upgrade while the company is forcing upgrades. If or when you get displaced to CA then the next bid preference for an FO position and then subsequently get displaced during the displacement round. From there you can have the 175 CA position in your top displacement and hope to get the 175.

My last and final advice is to contact your union rep if you want bidding advice. Tell them what you want and they will point you in the right direction.