Just keep in mind that LH is actually good at this, so even if no seat has been assigned /possible to get during OLCI, it is still likely that she will get assigned a seat in C/J at the gate. Most pax with unassigned seats during check-in end up traveling exactly as booked once it is clear how many pax will misconnect, no-show, rebook last minute etc... My bet is that she will end up with a seat in C/J on the flight booked.