Question, When can I return to Ahm?

[Zartuul]

I got the 15,000 gp that I needed to go to the asylum and went with only 5 people because I wanted to get Imoen back ASAP since I was intending to make her my primary spell caster. However I want to get Mazzy into my group now but I have no idea when I can return to the overland map to do the quest where she's at. I just escaped the asylum and just now started the Kuo-toa area. When can I go back and do some unfinished business with the chapter two quests?

[LichSlayer21]

....................Minor Spoiler............

As soon as you exit the Underdark after doing the various quests and get the Silver Dragons Eggs Back after killing the Matron Mother and Phaere or you can sacrafice the eggs to the demon then go kill the Dragon and get the scroll to leave the underdark(the exit is in the Kuo Toa dungeon

[Zartuul]

So in other words you want all the NPCs that you want in your party BEFORE you go to the asylum? Sounds like an awful lot of adventuring you would have to do in order to return to Ahm once you go to the asylum.