PM who have approved
Is the phrase correct?
I think it should be "PM who has approved" (PM: Project Manager). Am I wrong?
Both might be ok depending on what PM means.
What is said above is correct. When you are taking PM as Prime Minister (singular), usage of has* is correct. But when it's regarding a group like project managers (plural), usage of have is right.
It's all about whether it has been referred to a single person or to a group. If plural, use have and if singular, use has;that's it.