I'm trying to make an NPC that's a Fighter(5)/Knight Protector (6). According to the Complete Warrior sourcebook, the requirements for the Knight Protector prestige class are:
Base Attack Bonus: +5
Skills: Diplomacy 6 ranks, Knowledge (nobility) 4 ranks, Ride 6 ranks
Feats: (not relevant to the question)
By the time a fighter hits 5th level, they can easily meet all of those requirements except the 6 ranks in Diplomacy - they can't meet that until they're 12th level because it's a cross-class skill.
I'm looking at the Half-Elf Fighter racial substitution levels from the Races of Destiny book because they offer Diplomacy as a class skill if taken at 1st and/or 2nd level. However, the next racial substitution level is at 6th level. I know that if I took the fighter to 6th level and used the racial substitution level then I'd get the ranks in Diplomacy but I'd like to avoid that route.
My question therefore is, once the half-elf racial substitution levels make Diplomacy a class skill, does it stay a class skill for later levels of fighter? That is, if the fighter hits 5th level is their maximum number of ranks in Diplomacy 8 or only 4 ? My understanding is that for normal multiclass characters, it would be 4 but the text for racial substitution levels states specifically that taking a racial substitution level is NOT multi-classing.
I'm grateful for any help.