Complex sentence: Michael attempts to apologize to Holly, but when she declines to talk, he has her join Kevin and Creed in his office so he can apologize to the two of them, simultaneously apologizing to Holly indirectly.
Split into simpler sentences: Michael attempts to apologize to Holly, but she declines to talk. He has her join Kevin and Creed in his office so he can apologize to the two of them, simultaneously apologizing to Holly indirectly.