Falavar_Flyverin

So right now I'm at the beginning of chapter 15 with Thany at level 20/5, Shin at 20 unpromoted and Sue at 1 unpromoted, and I killed Klein and Tate as enemies because I didn't want to use them. Apparently, I need the total exp of Thany and Tate to be lower than the total exp of Sue and Shin in order to access the Sacae route (and enable me to get the legendary bow), so my question is this: If Sue and Shin's total exp is lower than that of Thany, does that mean I'll automatically go to Ilia's route, or am I shunted to the Sacae route due to Tate's death? If Ilia's route happens, it's my understanding that as Tate is dead I won't be able to access the ice spear gaiden chapter and thus the good ending. I want to access the good ending so if possible I'd like to go on the Sacae path, but Sue is too weak to train (gets one-shotted by everyone) and I have no Orion's Bolts for Shin. Is the only way to get the good ending at this point to go through the arduous process of baiting last hits with Sue and rescuing her until she reaches level 8-9-ish in the next couple of chapters?

So right now I'm at the beginning of chapter 15 with Thany at level 20/5, Shin at 20 unpromoted and Sue at 1 unpromoted, and I killed Klein and Tate as enemies because I didn't want to use them. Apparently, I need the total exp of Thany and Tate to be lower than the total exp of Sue and Shin in order to access the Sacae route (and enable me to get the legendary bow), so my question is this: If Sue and Shin's total exp is lower than that of Thany, does that mean I'll automatically go to Ilia's route, or am I shunted to the Sacae route due to Tate's death? If Ilia's route happens, it's my understanding that as Tate is dead I won't be able to access the ice spear gaiden chapter and thus the good ending. I want to access the good ending so if possible I'd like to go on the Sacae path, but Sue is too weak to train (gets one-shotted by everyone) and I have no Orion's Bolts for Shin. Is the only way to get the good ending at this point to go through the arduous process of baiting last hits with Sue and rescuing her until she reaches level 8-9-ish in the next couple of chapters?