when you find a new henchman, talk to him and tell him your looking for a merc, pay what
he wants and violla, multi henchman, this way wou can build up your own private army.

Up to 2 Henchman, one pet, and one familiar.
On Multiplayer you can get two henchman, one familiar, one pet, and up to three PCs, I
tried it and it worked.

I have one henchman, I talk to another and pay what he/she wants, and my first henchman is
removed from the party and the second henchman takes his/her place. I figured it was only
possible to have one henchman, one familiar, and one summoned creature. Is it actually
possible to have two henchmen?

I was able to, on multiplayer, have two friends, a summoned creature, an animal companion,
a familiar, two henchmen, and me, all on the same team, a total of 8 party members.

If it's you and two friends, that's 3 members. And it's easily possible for one person to
have a familiar, a summoned creature, and a henchman. That's 6 members total. And then one
of your friends is a ranger with his animal companion and his own henchman (mind you, I've
never played multiplayer, so I'm guessing at how multiplayer works with henchman), and
that makes 8.

But what about single player? The most I've had for a single player party is one henchman,
one familiar, one summoned creature (I've never tried to summon a second creature while I
still had the first). I suppose it's conceivable to have a familiar and an animal
companion if you're a ranger/wizard or ranger/sorcerer. If so, that would be animal
companion, familiar, summoned creature, and henchman. But I'm more interested in having
more than one henchman. Familiars don't fight as well as henchmen.

I got two henchmen, an animal companion, a familiar, and a summoned creature. Yes, I
multi-classed too much.

How did you get two henchmen? The familiar, animal companion, and summoned I understand.
But how do you get two henchmen on single player? For me, it always just replaces the
first one with the second.

Can only keep 1 henchman in my group at a time. I first hired the rogue in the temple,
then went to the tavern to hire the cleric, but when she joined, the rogue left. Put him
back in the party, cleric leaves. :(

Plz tell me this is a known bug, cause i'm gonna be disappointed if it isn't, for as old
as this game is now.

You can only have 1 henchman in the original campaing (in the expansions its 2)

You!!!!!!!!!!!

Why don't you just edit the campaign modules? That could work.