I am travelling on British Airways but with AA 001 tickets. Will I be able to get an AUP or ask for any sort of upgrade at the check in counters? Online is impossible as it's an economy basic fare and neither airline is offering anything.

Two scenarios:

WAW-LHR (BA operated) transferring to LHR-MIA (AA operated - on one AA ticket) - can I ask for an upgrade for second leg at Warsaw, or only in London but at gate when connecting?

MIA-LHR-WAW (all BA operated on AA ticket) - want to upgrade the long haul leg - would I be able to at Miami check in counter with this AA ticket?

Many thanks!