How to validate a People Picker control when comparing to a Multiple Selection People Picker control using a rule in Nintex Forms?
To check if a person from one people picker control exists in a selection of people in a people picker control that allows multiple selections the contains() runtime function needs to be used in the validation rule.
Example : contains(MultiSelectPP,PeoplePicker)
If the equals() runtime function is used the validation will only work when there is one person in the multi select people picker. As soon as a second person is added the validation will fail as one people picker will not equal the other even though it may contain a matching person.