Tried calling them?
I have previously asked QF for the SB PNR, and they have provided it.
Depends on the nature of the code share arrangement.
Some simply allow the marketing airline to sell a certain number of seats. Some are more complex.
On QF flights between SYD and SCL for example, LATAM buys blocks of seats from QF and pax booking the LA flight number will only be seated in those blocks. Conversely, pax booking the QF flight number will not be seated in those blocks, even if this prevents an upgrade, for example.
However when the flight closes it becomes a free for all, which means LATAM can sell upgrades into QF's seats on checkin at SCL airport. Meaning QF staff often manage to get a spare business seat SYD-SCL (because QF do not sell upgrades at checkin) but almost never SCL-SYD because any spare J seats are sold by LATAM at checkin. (Thankfully LATAM doesn't sell upgrades to premium economy, usually sparing them the indignity of a seat in whY.)
Returning to the topic, if the block of middle seats is allocated to QF, then you may not be able to be allocated a seat outside that block, such as a window seat. But this might change once checkin opens or, later, when the flight closes.