For years folks have been saying Pat picked Holly to replace her, but if you read Pat's last book, Pat doesn't say that at all. She tells a totally different story.
If I recall correctly, they go on vacation and while walking on the beach, Holly tells Pat that she wants to succeed her. She wants the job and Pat's response seems to be "umm...ok." And she goes along with it. It is not stated like Pat suggests it, it appears to be all Holly's idea.
While reading that, to me, it felt like Pat didn't want to hurt Holly and basically agreed with it.
Maybe someone with better info can shed light on this?