I had heard there were characters (party members, potentially) that were added to this by Beamdog that weren't in the original game. What are their names?

According to Wiki: Baldur's Gate, the new companions are:

---

New companions BG:EE

Baeloth Barrityl • Dorn Il-Khan • Neera • Rasaad yn Bashir

---

New companions Baldur's Gate II: EE

Clara • Dorn Il-Khan • Hexxat • Neera • Rasaad yn Bashir • Wilson

---

technically Clara and Hexxat are the same person and they are both pure thief... and buggy

its very hard to get him but Wilson is great bit of fun

main characters you can take from start to end;

Dorn has a very hard quest line

Rasaad is totally worthless

and Neera is my fav romance but her questline can be hard

there is also sod characters;
Corwin [archer]
Glint [thief/ cleric]
Baeloth [sorcerer]
M'Khiin [sharman]
and Voghiln [bard] of which Corwin is easy the best

What does sod mean (other than a Japanese publisher of adult videos)?

Siege of Dragonspear.

https://www.gog.com/en/game/baldurs_gate_siege_of_dragonspear

Thank you. I should have thought of that. Never played it.

No problem :)