[Faceman]

There actually is a non-cheating (yet cheesy) way to get rid of Melchor Harpell and keep Drizzt stuff for good. Just make your main char immune to Imprisonement (Spell Immunity Abjuration or Rage). Melchor will not attack further and stay at his current position forever. Now cast Freedom to get your party members back and leave with the loot from Drizzt and his friends.
You can even kill him in earlier SoA versions using the Nishruu bug (Nishruu eats up every magical item even with permanent effects) to remove Imoen's belt (Melchor wears it to be virtually invulnerable). To do so it helps to have your Nishruus/Hakeashars ready and attack him immediately at warping in, while casting time stop to kill him when he has lost the belt and before he casts imprisonement
All this workarounds however hold a certain chance of trashing your dialogue options afterwards (i.e. all dialoges automatically finish instantly --> no buying, no quest talk, ...)