Hi,
I have a trip booked via Turkish Airlines that includes 3 flights for 2 people. The last one is a codeshare operated by Malaysia Airlines from Kuala Lumpur to Perth, economy cabin.
We would like to choose/buy seats for this last flight, however we are unable to do so, TK website and app do not allow us to view the seatmap. I managed to get PNR in MH system, I can log in but unfortunately same issue exists - error when trying to view seatmap.
The helpdesks are not able to do anything, MH people say that this is expected for codeshare flights. What worries me is that they also say that check-in will be available only at their airport check-in counter. And here my questions arise, maybe someone already went through similar story:

Is there any workaround for this?
Will I be able to check-in online for this one flight (despite what helpdesk guy says) via MH app/website and choose seats then? (I guess TK online check-in will fail for this particular flight?)
What if online is impossible at all? Will I need to go to some transfer center to get boarding pass? And then is there a chance that me and my flight partner will be seated separately?

Thanks for any answers