adding a cgi rockmen sequence
"Galaxy Quest" already did that one, anyway.
My ST pals and I were in hysterics throughout a preview screening of "Galaxy Quest" and at one point, after the baby aliens turned into sinister gargoyles (Shatner had wanted hundreds of gargoyles in ST V), I had actually leaned over and said, "All we need now is a big orange rock man..." - and in he came!
The problem with Sybok is his blood relation to Spock isn't of fundamental importance to the character. Make him Spock's long-lost childhood friend and the story is mostly unchanged. Moreover, it's awfully late in the game to be introducing long lost relatives of the principal characters.
Diehard TOS fans were upset because DC Fontana had issued memoes during TOS that "Spock has no siblings", because they didn't want his uniqueness to be diluted, and it seemed that numerous writers were pitching scripts featuring Spock relatives. When Shatner announced his intentions for ST V, both Roddenberry and Fontana objected publicly. Fontana also slipped a mention of "Spock is the only son of Sarek" into her novel, "Vulcan's Glory".