Thank you for amending your initial post to add in some specifics.

This is the thread you need to look at (and to summarise, BA takes the hardest line here, even on codeshares that land in their court) for baggage but these fares allow seat selection for most status passengers in most scenarios.
https://www.flyertalk.com/forum/brit...announced.html

and this is the chart you need (hat tip [MENTION=53393]ianwall[/MENTION] ). Just follow the zeros. The chart is poorly labelled, but in essence go down the first column for your marketing flight code airline. Then go rightwards to find the operator / metal for your status.