This is an award reservation in Lufthansa that I used my miles to book for my mom from Bahrain to SFO with 1 connection at FRA. I'd ideally want her to sit in the exit row seats, but exit row seats are released just 48 hours before the departure. And I can't pay & reserve the exit row seats too, which means she needs to go to the airport 48 hours before to check-in, is it?

She went today to the Lufthansa office in Bahrain to know how she can get exit row seats, they mentioned it is first come first serve basis and asked her to come anytime 48 hours before departure.
Even if she goes to the airport 48 hour prior, her second leg of the travel, (which is FRA to SFO is 13 hours long), they will not guarentee the exit row seats yet, because it is not 48 hours prior in FRA local time.She is getting little nervous about it.

I'd appreciate any help from you if there can be some way to get the exit row seats.