For this example, let's assume you want your final build to be a Paladin2/Bard18.
1a) Start your character as a fighter with alignment Lawful Good (Ftr1 LG).
2a) Take another level in Fighter (Ftr2 LG).
3a) Multiclass to Paladin aboard the Reincarnation boat. Before you hit Finish, change your alignment to True Neutral (Ftr2/Pal1 TN).
4a) Multiclass to Bard (Ftr2/Pal1/Bard1 TN).
5a) Lesser Reincarnate +1 your character.
1b) Roll your character as a fighter (Ftr1 TN).
2b) Change your alignment to Lawful Good. (Ftr1 LG).
3b) Level up as a Paladin. This will use your change from LR+1. Before you hit the Finish button, change your alignment back to Neutral (Ftr1/Pal1 TN).
4b) You are forced to level up as a paladin, since you are out of class changes from your LR (Ftr1/Pal2 TN).
5b) Forced to level up as Bard. (Ftr1/Pal2/Bard1 TN).
6b) Lesser Reincarnate +1 your character.
1c) Roll up your character as a Bard. This uses your only level exchange from LR+1 (Bard1 TN).
2c) You are forced to level up as Paladin (Bard1/Pal1 TN).
3c) You are forced to level up as Paladin (Bard1/Pal2 TN).
4c) You are forced to level up as Bard (Bard2/Pal2 TN).
This gives you a Bard2/Paladin2 with the proper alignment to continue leveling up as a bard.
Of course, since we are playing in Eberron we should not have alignment-restricted classes anyway:
Quote:The tone provides a portion of what sets this campaign apart from other D&D worlds, and this was first and foremost in mind as we built the complex tapestry that is the Eberron Campaign Setting.
Quote: Alignments are relative guages of a character or creature's viewpoint, and not absolute barometers of affiliation and action; nothing is exactly as it seems. Alignments are blurred, so that it's possible to encounter an evil silver dragon or a good vampire.
Quotes are taken from Eberron Campaign Setting, Page 8. Context:
The Tone of Eberron and
Ten Things You Need To Know.