So I'm reading the CO website trying to find out the rules on baggage allowance. For First and BF, it has the following to say (emphasis mine):

3 Checked Bags: Maximum 70 lbs (32 kg) and 62 linear inches (157 cm) (total length + width + height) per piece. Ticket must reflect confirmed seat for segment in which customer is checking in.

I read this to mean that, as long as you have an F or BF seat, regardless of whether it was obtained via purchase or upgrade, that you can check a 3rd piece. Does anyone have any experience that would confirm or refute this thinking?