1. Keep Cecil (removing the cartoon Logan Rhinewood silliness); keep him as a business rival of Blake's who realistically plays an intelligent game of chess with Blake over the entire series.
2. Allow Alexis to develop as a sideline schemer - and allow her amoral/asocial character to surface more frequently. Let her be a real wild card, trustworthy to no one including Cecil.
3. Make the Dominique story result in serious vendettas against all three major players - Blake, Alexis and Krystle. Never incorporate Dominique into the inner trusted core of the family - instead, shed be a strategic partner for some plots but a rival/barrier in others. She should be allowed to always hold some grudges against the other character's refusal to accept her presence as an equal player or family member.
4. Allow Blake to outwardly state the real reason he didn't accept Dominique as his sister: her race. Allow Blake's bias against Dominique to explicitly surface and be a plot point driving conflict between him, Steven and Fallon. Adam could easily have been painted as jealous of yet another claimant to the family fortune and easily un/consciously racist as well.
(It truly drove many of us crazy watching Dominique's entrance into the series when the obvious issue of racism was never mentioned or made clear, when it absolutely would have been named in real life.)
5. Keep Sable. Never, ever sideline Sable. Make her be the even
wilder wild card than her sister - selfish, a twinge of morality and inner conflict, but also capable of truly hateful deeds driven out of sibling rivalry.
Gee, I wish I had a time machine right now.