I always thought we were given enough on-screen hostility between Jacqueline and Angela in the first two seasons to know that Jacqueline was a very evil and heartless woman
I'd need to rewatch it for the third time, but I'm not sure if
on-screen Jacqueline was ever truly established as a villain, but more like a woman who had made some bad decisions and now had to face the fact that her two sons (believing to be cousins) had become enemies.
Let's not forget that Angela still had the power to blackmail Jacqueline, the kind of blackmail that really
shouldn't impress the head of a powerful Nazi-originated cartel.
Most of the aggressive attitude seems to come from Richard and Angela, not Jacqueline.
As with Julia as the killer I don't think it was planned ahead that Jacqueline was going to be the Cartel's Number One. It was a fabulous reveal and yes it did describe Jacqueline as a power-hungry woman (like her former sister-in-law) but two minutes later Richard started to threaten Chase and his family - and suddenly Jacqueline's power meant nothing anymore.
Unless, as Richard suggested, she would have him killed.
Sure, everything about Richard's upbringing was wrong, but the story is also very much about "the enemy of my enemy" and since I was rooting for Chase - and certainly not for Richard who had already proven to be a dangerous and ruthless man - Jacqueline ended up in the "good camp" by default.
Ironically, her (grand)maternal instincts had always been stronger than Angela's.
With Richard dead, the adventure with Douglas could continue and the heir would be Chase
A male heir was not required, Angela herself was the proof of that. Besides, Chase would only inherit the part of his father. As he did.
Still, a resourceful woman like Jacqueline could have made it work somehow but since she didn't I'm not sure she was ever all that interested in Falcon Crest.
I think the best part about the Cartel is how it was intertwined with the Carlo Agretti murder mystery.