Back in June 1993, while patching Forgotten Realms – Unlimited Adventures to version 1.2, a bug in the included sample adventure module Heirs to Skull Crag was introduced. This has left the adventure unfinishable, in that a required quest event now fails to trigger.

I have just ascertained that the following method of correcting this does work, and it works with existing savegames from before the your party delivers the second quest item to its respective quest giver.

To apply this fix, we want to edit the module itself. This is what it’s included for, after all, the fun of its playability is only secondary. Very mild spoilers follow.

What we need to do is bump up a value threshold at each of the three quest givers.
Don’t worry if you go where you’re not supposed to be, you can always safely Cancel yourself out of there.

From the start menu screen, while HEIRS.DSN is selected, choose to Edit Modules.

The Sword of the Roadwarden
From the adventure module list, select and Open DUNGEON 02 - SKULL CRAG TOWN.
Now we’re in what I consider the main view of the suite.

First, make sure we're in the right modes. Click and hold the MAP button in the top middle, drag the mouse cursor down to AREA VIEW. Then click/hold once more on the MAP button, and now select EVENT PLACEMENT.

With the mouse cursor, find the white square cell at the coordinates COL 9 ROW 6, a little above the middle center. It should say Quest Stage. Click it, or tap the Uparrow key six times to move the yellow arrow down into the cell, then Edit Event by pressing E.

Now we’re going to do some event chain tree traversing. Keep your footing steady!
In the following screen of several events, starting with a Quest Stage event as current, hit the Downarrow key or Next once to make the Current Event (Alt 1 of 3) a Text Statement. Then press A for Alt to switch to (Alt 2 of 3), a different branch. Now hit the Downarrow key or press Next seven times to make another Quest Stage the Current Event. Choose Edit. The image attached to this post is the screen you should see.

Now for the actual editing. With the mouse cursor, select the box where it says STAGE: 3 and enter 4 instead. Finish by choosing OK.

In the main screen again, hold the mouse button down when pointing at the upper left FILE menu button to get a dropdown menu, and choose Open...

Back at the adventure module list, select and Open DUNGEON 04 - SKULL CRAG KEEP

When suddenly prompted
SAVE CHANGES TO CURRENT MODULE?
Don’t worry. Choose to Save. It’s okay.

The Lance of the Roadwarden
We’re in the Keep.
Leftarrow, then 6xUparrow, then Edit. Or click the white cell at COL 3 ROW 27, the one closest to the down left corner.

The next steps are identical to the ones for the Sword:

In the following screen of several events, starting with a Quest Stage event as current, hit the Downarrow key or Next once to make the Current Event (Alt 1 of 3) a Text Statement. Then choose Rightarrow or Alt to switch to (Alt 2 of 3) again. Now hit the Downarrow key or press Next seven times to make another Quest Stage the Current Event. Choose Edit. The screen looks like the previously mentioned screenshot again.

With the mouse cursor, select the box where it says STAGE: 3 and enter 4 instead. Finish by choosing OK.

Lastly, a special case:

The Shield of the Roadwarden
In the main screen again, hold the mouse button down when pointing at the upper left FILE menu button to get a dropdown menu, and choose Open...

Back at the adventure module list, select and Open
DUNGEON 21 - KEEP-KALLITHREA
The cell we want is at COL 19 ROW 20, middle right on the map.
Next, Alt, Next Next Next Next, Edit gives you the now familiar dialog box screen. You can also enter the secret cheat code ↓→↓↓↓↓E. Change STAGE: 3 to 4 again. Finish with OK.

Hold your mouse button down when pointing at the upper left FILE menu button to get the dropdown menu, and select LEAVE from this menu.

SAVE CHANGES TO CURRENT MODULE?
Choose to Save.

And we're back at the start screen, ready to win Heirs to Skull Crag!

Here’s where I found the solution. All hail the tireless hackers of the FRUA/DC community:
http://ua.reonis.com/index.php?topic=819.msg6189#msg6189

Finished "Heirs to Skull Crag" normal-play recently (Under UASHELL) and sorry but the game has no bugs, as far as I know.

After you recovered the two arms you must rescue Morudel. And after everything about the rescue is done, Morudel says "sadly there's still arms to recover". It's time to recover the third arm. Go to the correct remaining character's place (Kallitrea, Dazmilar or Yemandra) to accept the last arm quest. If you are unable to find the character in his place try at the night fall and before midnight, for example. The hour is sometimes important on the Gold Box games.

Remember that the place of every quest is created after you accept that quest, or you will be unable to find the place on the map. The clues about the places are on the old man you find on the map north of Skull Crag, he says something like Minotaurs from North, Giants from SW and Ogres to SE followed to the South Sir Dutiocs (from he's standing).

Always pay attention to the texts of the game. On the first talking about the arms, you will discover there's a four arm: Arelin's helm. This game is a complete game, not just a demo as many people thinks. So it's bigger than a simple demo. After you recover the third arm, it's time for the helm. To complete the helm's quest you must open the doors with three locks located inside the Minotaur's labyrinth or the giant's labyrinth (next to the Wyrm's Lair). After that searching walls you will find a secret door, a secret entrance to a underworld with walls of flames. Follow the mysterious character you find there and that is running on the corridors. Follow him ALWAYS until you catch him. You will fight a lot of monsters to stop you (including a Beholder or a giant Iron Golem). Following him correctly you will reach the dungeons of Skull Craig Keep. Be aware that the Area option will be disabled at this point on the dungeons, so if you enter previously here draw a map.

If you do everything correctly, at the end two consecutive great battles take place on the Skull Crag's Great Hall. After winning the two battles, the game ends succesfuly. Between the two battles you can only heal, so before go directly to the Great Hall take a door to the Guests rooms and rest to memorize spells. Go to train also, to the west from the entrance of the keep, the building's second door.

There are places on the three labyrinths to rest. In this way you can rest without go back to Skull Crag. The game informs you if it's a resting save place. Usually are abandoned rooms with dust, or for example the Wyrm's lair after kill the Wyrm.

Before I forgot, the rare keys to open the doors with 3 locks are on the 3 labyrinths of the 3 arms' quests from the characters. One rare key hidden on every labyrinth.

In fact there are resting places in a lot of places. A little hidden or not (like the Lizard men city, the resting place is i n a clear after a little labyrinth on the swamps),