[FE6] How to add new classes without replacing old ones

Recently I’ve been getting into romhacking and want to create my own original story one day, but first I’m trying to make a patch for FE6 to try and familiarize myself with the FEBuilder engine. The first thing I wanted to do was add a new promotion for Roy, making him a Knight Lord instead of a Great Lord. At this point I’m fully capable and know how to add my own classes, I’m having no trouble doing that, it’s something else that’s gotten in the way. I’ve been told for both FE6 and FE7 if you add more class slots than the unedited rom comes with, it’ll break the game and that the only way to add new classes is to replace existing ones. I have no problem with replacing the Great Lord class with the Knight Lord class, it’s just I wanted to add a few others as well, and I don’t know if I’ll have enough.

The whole “the game will break if you add more class slots” thing, is it true?

i dont think you must replace class to do

Maybe they were able to add new class slots to the rom after all? I’ll try asking them, but I don’t know if they’ll respond or not because this post is from a few years ago.

no, unless the tool you are using is bad at it.

(this is partially true in FE8 because the vanilla game hit the cap the engine handles without additional hacks (127/7F) but not in FE6)