What to do?

I have a serious problem.

Have made a multiplayer game with my own berserker, mage, fighter/cleric, Minsc, Jaheira and Imoen.
Now I have reached Waukeen's Promenade in chapter 1 where Imoen have been captured. My problem is I have no thief now. No one to open locks and detect traps.

I have 2 questions now.

Can I complete chapter 2 without too many problems without a thief?

I have killed the group of adventures on the top floor of the Den of Seven Vales. There are two locked chests in that room but witout a thief I can't open them. Are there any good things in those chests and if, is it possible to come back later in the game when I have rescued Imoen to collect the things?

[Aurum]

Nalia or Yoshimo, not very good, but you serv???

Possible, but suffer you great damage.

wizards have a knock spell, and wizards and clerics have find traps Divination, try those, if you don't have those spells, try the Adventurer's Mart, by the way, you're not getting imoen back for a long time, you may just want to make a thief character

[Tobbin]

If I remember correctly (maybe not, I'm not sure) Jan Jansen is a thief mix. You could use him. You gotta help him with some stuff first, but nothing too taxing. If you don't want to go this route, you may want to try HalfKnight's suggestion. Making your own thief will give you total flexibility. You can set him/her up with whatever stats you want. Plus, most characters that you find don't have any good items anyways, so you can just pass them what you need. Buy some armor and some weapons for them and they are just about as good as a NPC. Too bad that you didn't pick up Yoshimo though. He is a pretty good NPC (in the beginning at least). Good luck with whatever you plan though.

You should have Yoshimo in your party at this point who can open locked chests. He also has 100% detect traps ability which you should have turned on at all times. If you have lost Yoshimo then go the copper coronet in the slums and find Nalia, She is a second rate theif but will do until you find better. You will also have to do her quest to kep her.

[Tobbin]

I tried to just go it alone with using a mage to simulate a thief (invisibility, knock, etc.), but I just had to keep resting too much in those dam*able dungeons and such not. I was getting royally whacked, since I couldn't use my spell slots too. Potions and scrolls helped out a bit (as well as rings), but really, nothing can compare to using a thief.

[Zoratorak]

you can always try to FORCE the locks...

[Tobbin]

Yeah, I've tried that too, but a great many of them can not be forced. And since I didn't tweak my Str, I have 18/30, I don't make a lot of str checks against locks. When I cast Knock, it almost always opens the thing, but then I gotta use a spell slot for that. And usually I find more than one item I can't get into, so I memorized two of them. Got tired of that, so I just created a thief and started raising her in levels. I didn't know I was gonna get IMOEN back, and I had named her the same and gave her the same picture. It was really awkward for awhile. I took someone's advice and raised her to a 10th level thief and then dual'ed her to a mage. Ah well. Wish I could have kept her, but I was afraid I would miss out if I didn't have the real one.