Re: Does Divine Grace and Dark Blessing still stack in NWN2?
"A paladin who ceases to be lawful good, who willfully commits an evil act, or who grossly violates the code of conduct loses all paladin spells and abilities (including the service of the paladins mount, but not weapon, armor, and shield proficiencies). He may not progress any farther in levels as a paladin. He regains his abilities and advancement potential if he atones for his violations as appropriate."
I've never tried it, but I would assume that divine blessing to dark grace would stip the paladin of his abilities.
Don't know about the other way though...