Simple Q&A D&D 3.5 (by RAW) XXII

[Phelix-Mu]

Q170

A character starts with x levels in some class that doesn't have Jump as a class skill. Then the character multiclasses into a second base class that does have Jump as a class skill. Am I correct in thinking that maximum ranks in Jump is still equal to (character level + 3)? Is there a difference if the second class is a prestige class?

Corollary: Doesn't this make language in feats like Draconic Knowledge, "All Knowledge skills are class skills for all of your classes," unnecessary, since being a class skill for any of your classes seems to make it a class skill for all your levels.

This issue continues to confuse me, usually because I am a DM making a 15th level npc with a bunch of skill points to spend and trying to figure out max ranks for a specific skill. Seems that there still should be an effective maximum, since skill points gained in the first x levels shouldn't be able to be spent on Jump as a class skill...but does retraining fix this? *pulling out hair*