Long story but I'll try and shorten it up:
took wifes laptop on vacation to play IWD2; forgot the manual and didn't have internet connection to check for information so when doing party creation I was thinking more along the lines of 2nd edition rules vs 3rd edition rules and thus made some mistakes that I want to correct before my party advances in levels much further.

Party consists of:
aasimar paladin (of helm)
human ranger
shield dwarf fighter
half-elf bard
deep gnome cleric (morninglordflathader)/illusionist
strongheart halfling thief

Everyone is lvl 10 except for the cleric/illus. who is 4/4.

Party is a little weak on healing and spellcasting so I'm looking for some suggestions on multiclassing the ranger, bard, and possibly the thief.

Figured the ranger would make a good cleric--found a potion to increase wisdom (at expense of dex.) since it is low. What would be the ideal lvl to turn her into a cleric? Will I be missing out on any good ranger feats? She is my archer but so far I'm not too impressed with missile weapons in this game. Figured if she becomes cleric I'd buff her with spells and send her into battle dual wielding.

As for the bard figured after getting her last bard song at 11 to turn her into a sorcerer. Is this a good or bad idea? Again, what would be ideal level?

Lastly, the thief: there are a few more good feats I'd like to get but thought about possibly multiclassing him into a barbarian. Any suggestions? I primarily use the thief as a forward scout and initiate battles with him backstabbing.

I'm probably forgotting alot about multiclassing penalties and other do's and don't so forgive my noobishness.

Hmmm, how far through the game are you if your 6 person party is already at level 10? Realistically, your characters only have another 7 level-ups left in them in normal mode so the answers to your questions depend on whether you want characters to get you to the end of normal mode (thus we only need to worry about the next 7-8 levels) or whether you are trying to build characters who will be able to survive Heart of Fury (then you need to have the final 30 level builds in mind).

Your party is definitely low on spellcasting - especially offensive firepower. You do not have a 'bombardier' in your group. Plus you don't have anyone who can easily cast things like 'Heal'.

1) Ranger - you could multi to cleric. Depends on her wisdom. You certainly won't miss any good Ranger feats because there aren't any. By level 6, this cleric will benefit from 2 levels of Draw on Holy Power which will be a useful buff.

2) Bard to Sorcerer is debatable. Sorcerer benefits from Bard's Charisma but you lose the benefit of his songs if he's busy casting offensive spells. But given that taking Bard levels past 11 is next to useless, you might as well.

3) Rogue. Depends on his stats. I'll assume he doesn't have enough Int, Wis, or Cha to become a useful Wizard, Cleric, Monk, or Sorcerer. Therefore you are really only left with Fighter (4 levels for Weapon Specialisation) or Barbarian (for increased HP etc).

Anyway, it all depend on your playing style. If your tanks have good stats then they may well be able to clean up most of the encounters anyway (but they'll be toast in HoF).

Thanks for the reply.

I just got to the wandering village; I plan on doing some quests and get another lvl for my fighter and then go back and do the battle squares one more time. (most characters are within 1000xp or so of hitting lvl 11).

HOF mode sounds interesting but I have such a huge backlog of games to play yet I know I'll never get to it so more suggestions geared toward the next 7-8 lvls would be great.

Well, if you do multiclass your Ranger to Cleric, then you might consider taking all the rest of your Gnome's levels in Illusionist so that you at least have one member of your party able to access reasonably high level arcane spells.

That way, by the time you get towards the end your party might look a bit like this:

Paladin 13 / Fighter 4 (consider taking 4 levels of Fighter to get Weapon Specialisation)
Ranger 10 / Cleric 7 (other people will be able to better advise you on which cleric order to choose - probably Talos)
Fighter 17 (can't think of anything else to do with this tank)
Bard 11 / Sorcerer 6 (choose his spells very carefully as ones to complement his songs)
Lathander 4 / Illusionist 11 (as your only high level arcane spellcaster you may need to micro-manage the spells he learns before each encounter)
Rogue 10 / Barbarian 7 (not at all sure about this character)

Luckily you shouldn't encounter too many multi-classing penalties with this as all the favoured classes seem to be OK.

Also, with so many melee fighters, you might want to have them each get weapon focus in different weapons so that you get best use out of the various weapon types. Have your casters cast group level buffs like Strength of One to extract the best from your fighters rather than the one-to-one buffs which will take up too many spell slots.

aasimar paladin (of helm)
give him fighter levels and get weapon specialisation. since you arent going into HoF stick to Fighter[4]/pally[x]

human ranger
enough with the ranger levels. take druid or cleric. druid will get better summoning spells.

shield dwarf fighter
give him barbarian levels. more HP and rage are damn useful.

half-elf bard
bard[11]/sorcerer[x] is a useful multiclass. afterall the bard has very a bad spell selection.

deep gnome cleric
(morninglordflathader)/illusionist
continue in illusionist levels. you arent about to get the relly good cleric spells easily anyways.

strongheart halfling thief
wizard maybe. you need necromancy spells. or monk if ur wis modifier is +ve. this can make you a tank.

It depends on your stats. I'd say a rogue/wizard multiclass is very good, but you do need the intelligence for it. The same goes for almost all other multiclasses.

You may not be able to add Monk levels to your Rogue, it depends on your alignment. Definitely mix the Ranger up. I don't know why, but in IWD2, the Ranger really blows. I wanted to play one so bad because I loved them in IWD and I thought the dual weilding would rock, but that's the only advantage he gets and it's easy to obtain if using a fighter instead.

thanks for all the suggestions; hopefully I can lvl these characters up later tonight and put this advice to use!!